Catalytic Reactions of Terminal Alkynes Using Rhodium(I) - American

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Catalytic Reactions of Terminal Alkynes Using Rhodium(I) Complexes Bearing 8-Quinolinolate Ligands Fumitoshi Kakiuchi, Shotaro Takano, and Takuya Kochi ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.8b01286 • Publication Date (Web): 22 May 2018 Downloaded from http://pubs.acs.org on May 22, 2018

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ACS Catalysis

Catalytic Reactions of Terminal Alkynes Using Rhodium(I) Complexes Bearing 8-Quinolinolate Ligands Fumitoshi Kakiuchi*, Shotaro Takano, and Takuya Kochi Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.

ABSTRACT. 8-Quinolinolate is a monoanionic, hard, strongly σ-donating ligand and can form strong chelates with various metals. However, studies of the catalytic activities of soft transition metal complexes such as >2nd row, low-valent, late-transition metals having 8-quinolinolate ligands had not been well explored until recently. In recent years, several researchers including our group have studied and developed various reactions of terminal alkynes using rhodium(I) catalysts containing an 8-quinolinolate ligand. In this Perspective, we surveyed the transformations of terminal alkynes using 8-quinolinolato rhodium(I) catalyst such as additions of alcohols, amines, and thiols, as well as polymerization, trimerization, dimerization, and alkyne/alkene [2+2] cycloaddition. Mechanistic studies based on theoretical calculations of hydroalkoxylation of alkynes and alkyne/alkene [2+2] cycloaddition reactions have also been described.

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KEYWORDS: 8-quinolinolate ligands, terminal alkynes, hydroalkoxylation, hydroamination, hydrothiolation, anti-Markovnikov addition, alkyne/alkyne coupling, alkyne/alkene coupling

1. INTRODUCTION Homogeneous transition-metal-catalyzed transformations of organic compounds have become indispensable to modern organic synthesis, because they provide highly efficient, selective, and unique routes to a variety of organic molecules. A large number of catalytic reactions have been developed to provide various valuable compounds.1 In many of the reactions catalyzed by transition metal complexes, ligands on the metal centers play important roles to achieve high reaction selectivity as well as great reactivity and robustness of the catalysts. For example, if an oxidative addition step is turnover-limiting in a catalytic cycle, electron-donating ligands generally offer high catalytic activity. On the other hand, if reductive elimination is the turnover-limiting step, the use of -accepting ligands may be preferred. Organometallic and organic chemists usually tune the electronic properties and steric environments of the ligands to facilitate the desired transformation considering on the characteristics of the reactions and the transition metals.2 Various types of ligands including phosphines, pyridines, amines, carbon monoxide, isonitriles, alkenes, cyclopentadienyl derivatives, and arenes have often been employed as spectator ligands, and extensive studies have been conducted on how to optimize the reactivity of the catalysts by choosing the suitable class of ligands and fine-tuning their electronic and steric properties. However, progress toward expansion of the available classes of spectator ligands are still desired, as evidenced by how the emergence of N-heterocyclic carbenes (NHCs) have led to the developments of a variety of practical transformations in the past two decades.


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ACS Catalysis

8-Quinolinolate, which can be readily prepared by deprotonation of a hydroxyl group in 8hydroxyquinoline, is a well-known ligand for Lewis acidic metals, such as Al and 1st-row transition metals,3-6 but have not often been used as a ligand for soft transition metals, such as 2ndand 3rd-row low-valent late transition metals (Figure 1).7,8 In principle, it is difficult to achieve stable coordination of hard, anionic, strongly σ-donating ligands to soft, low-valent transition metals, which would even tolerate the conditions used for catalytic reactions, but we envisioned that the use of 8-quinolinolate ligands for complexes of soft, low-valent metals may be achieved, because of their strong chelating ability. If the nitrogen atom of the 8-quinolinolate ligand coordinates to a soft metal, the hard, anionic oxygen must present around the metal center, because there is no freedom of rotation around the bonds connecting the nitrogen and oxygen atoms. Therefore, there is high potential for formation of chelates robust enough for catalytic reactions even if it goes against the HSAB rule, particularly when it is assisted by the use of cationic metal centers to create electrostatic interactions. In addition, we speculated that this mismatched metal/ligand combination would provide unique catalytic activities which were not observed with well-studied matched combinations.

Figure 1. Metal Complexes Bearing 8-Quinolinolate Ligand

Our group has been studying the reactivity of the 8-quinolinolato rhodium(I) complexes with terminal alkynes. In addition, other groups have also reported on the reactivities of the 8quinolinolato rhodium(I) complexes toward terminal alkynes and the theoretical calculations of 3 Environment ACS Paragon Plus

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the catalytic reactions. In this Perspective, we briefly survey the studies on 8-quinolinolatorhodium(I)-catalyzed reactions of terminal alkynes up to the year 2017. It is important to note that syntheses and reactivities of 8-quinolinolato rhodium(I) complexes have been studied for a long time,7 but their application to catalytic reactions had been limited until recently. 8-Quinolinolato rhodium(I) catalysts have also been used in the reactions of substrates other than terminal alkynes such as Giuseppe, Castarlenas, and Oro’s -selective H/D exchange of styrene derivatives,9 as well as alkene oxidation,10 hydroformylation,11 and carbene polymerization,12 but these reactions are not covered in this paper.

2. ADDITIONS OF ALCOHOLS, AMINES, AND THIOLS TO ALKYNES Transition-metal-catalyzed addition of heteroatom nucleophiles to alkynes is a useful strategy for synthesis of alkenes possessing heteroatom substituents. There have been reported various transition-metal-catalyzed reactions to construct C(sp2)–O, –N, and –S bonds using alcohols,13 carboxylic acids,14 amines,15 and thiols.16 Recently, 8-quinolinolato rhodium(I) complexes were found to function as catalysts for the addition of heteroatom nucleophiles to form enol ethers, enamines, and alkenyl thioethers.

2.1. Synthesis of Enol Ethers by Addition of Alcohols to Terminal Alkynes Enol ethers are valuable intermediates in organic synthesis and are used for various transformation.17 The reaction of alkynes with alcohols is one of the most straightforward, atomeconomical strategies to access enol ethers and has been developed previously.18-22 The use of strong bases for the reaction is a simple method to synthesize enol ethers, but harsh reaction conditions

are

required

(eq

1).18

While

transition-metal-catalyzed


intramolecular

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ACS Catalysis

hydroalkoxylation of alkynes have been studied extensively,19 the corresponding intermolecular version, especially the addition to terminal alkynes, is still difficult to achieve.20-22 A PdMo3cluster catalyzed addition of alcohols to electron-deficient terminal alkynes gives antiMarkovnikov addition products (eq 2).21 A ruthenium(II)-catalyzed reaction of a terminal alkyne with allyl alcohol provides a mixture of the corresponding an anti-Markovnikov hydroalkoxylation product and its Claisen-rearrangement product (eq 3).22 However, no methods was available for the anti-Markovnikov addition of alcohols to unactivated terminal alkynes with high product selectivity.

In 2011, our group reported on the Z-selective anti-Markovnikov addition of alcohols to terminal alkynes using a rhodium(I) complex, (2-Me-Q)Rh(CO)2 (1a), which possess a 2-methyl-8quinolinolate ligand (abbreviated to 2-Me-Q) and two CO ligands, as a catalyst.23 It is important


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to choose a ligand, a solvent, and a reaction temperature appropriately to achieve high selectivity and efficiency. When the reaction of phenylacetylene (2a) with an excess amount of methanol (3a) was carried out in the presence of 5 mol % of 8-quinolinolato rhodium(I) complex 1a at 70 ºC in DMA, anti-Markovnikov addition product 4aa was obtained in 80% yield with a 90 : 10 Z/E ratio (Table 1, entry 1). Substituents on the quinolinolate ligand (abbreviated to Q) affected the catalytic activity, and the use of (Q)Rh(CO)2 (1b), which has a parent quinolinolate ligand Q, decreased the yield to 67% (entry 2). A phosphine complex, (2-Me-Q)Rh(CO)(PPh3) (1c), did not show any catalytic activity under the reaction conditions (entry 3). The addition reaction using arylacetylenes bearing an electron-withdrawing group at the para position proceeded smoothly to give the corresponding enol ethers in high yields (entries 4-7) with excellent Z/E ratios. In contrast, the reaction of p-methoxyphenylacetylene (2f) needed an extended reaction time to obtain 64% yield of product 4fa (entry 8). Tritylacetylene (2g) reacted with 2a to give the corresponding enol ether 4ga with complete Z selectivity (entry 9). This addition reaction is sensitive to steric bulkiness of alcohols. The addition of ethanol (3b) in the presence of 5 mol % of methanol required 72 h to achieve full conversion of 2a (entry 10).


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ACS Catalysis

Table 1. anti-Markovnikov Addition of Methanol to Terminal Alkynesa

4

yield of 4b

Z/Ec

C6H5

4aa

80%

90/10

2a

C6H5

4aa

67%

–e

3f

2a

C6H5

4aa not detected

4

2b

p-F3CC6H4

4ba

92%

94/6

5

2c

p-NCC6H4

4ca

85%

95/5

6

2d

p-MeO2CC6H4

4da

82%

94/6

7

2e

p-O2NC6H4

4ea

73%c

94/6

8g

2f

p-MeOC6H4

4fa

64%

87/13

9

2g

Ph3C

4ga

69%

100/0

10h

2a

C6H5

4ab

72%

91/9

entry

2

1

2a

2d

R

–e

a

Reaction conditions: 1 mmol 2a, 1 mL 3a, 0.02 mmol 1a, 1 mL DMA, 70 °C, 48 h. b GC yield of the mixture of Z- and E-isomers. c Determined by 1H NMR. d (Q)Rh(CO)2 1b was used instead of 1a. e Not determined. f 1c was used instead of 1a. g 7 days. h Performed with ethanol (3b) and 5 mol% of 3a for 72 h.

Wang and co-workers studied the mechanism of the hydroalkoxylation reaction based on DFT calculation and proposed the catalytic cycle as shown in Figure 2.24 Coordination of an alkyne to 1a gives rhodium complex 5, which then tautomerizes to a vinylidene rhodium complex 6 via an indirect 1,2-hydrogen shift. Nucleophilic attack of a methanol (3a) oxygen to the electrophilic carbon of the vinylidene ligand provides -methoxyalkenyl complex 8. In this step, the oxygen atom of the quinolinolate ligand directs the nucleophilic attack of 3a through hydrogen bonding (7 → 8 → 8’). Alkenyl complex 8 is converted to Fischer carbene complex 9 by proton transfer from the 8-quinolinolate oxygen atom, and subsequent rate-determining 1,2-hydrogen shift provides -bound enol ether complex 10. Ligand exchange between the -bound enol ether and 7 Environment ACS Paragon Plus

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2a produces product 4aa with regenerating catalytically active species 5. In their proposed catalytic cycle, the oxygen atom of the quinolinolate ligand is suggested to play two important roles: a base to direct the nucleophilic attack of methanol to the vinylidene ligand (6 → 7 → 8) and an acid to form -methoxy carbene intermediate 9. The observed Z-selectivity is considered to originate in the steric repulsion between the 8-quinolinolato rhodium framework and the phenyl group in the transition state of the rate-determining 1,2-hydrogen shift step. Messerle and coworkers reported on a similar hydroalkoxylation of terminal alkynes using a rhodium catalyst bearing an anionic N-N bidentate ligand, 5-phenyldipyrrinate, but their reaction proceeded with E-selectivity.25 Based on Wang’s calculation, the product formation in the 5-phenyldipyrrinatorhodium-catalyzed reaction occurs via reductive elimination, rather than 1,2-hydrogen shift, and the observed E-selectivity can be explained by the steric repulsion between the alkoxy group and the phenyl group.24b


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ACS Catalysis

Figure 2. Proposed Mechanism of the (2-Me-Q)Rh(CO)2-Catalyzed Hydroalkoxylation of Terminal Alkynes Based on the DFT Calculation


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2.2. Synthesis of Enamines by Addition of Secondary Amines to Terminal Alkynes Transition-metal-catalyzed hydroaminations of alkynes with primary and secondary amines are convenient methods for the synthesis of imines and enamines without loss of any atoms.26-28 While various intermolecular coupling reactions of alkynes with primary amines to form imines have been developed using transition metal catalysts,26,27 the corresponding reactions with secondary amines to prepare enamines are still limited.26,28 In 2011, our group reported on the 8-quinolinolato-rhodium-catalyzed anti-Markovnikov hydroamination of terminal alkynes using secondary amines to give E-enamines.29 When the reaction of phenylacetylene (2a) with piperidine (11a) was conducted with 10 mol % of (Q)Rh(cod) (12) and 20 mol % of P(p-MeOC6H4)3 (13a) at room temperature, anti-Markovnikov addition of 11a to 2a proceeded efficiently to give enamine 14aa in 85% yield (eq 4, entry 1). Both cyclic and acyclic secondary amines can be used for this hydroamination reaction. The reactions using N-methylpiperazine (11b) and N-benzyl-N-methylamine (11c) provided the corresponding enamines 14ab and 14ac in 82 and 73% yields, respectively (entries 2 and 3). Only E-isomers of the hydroamination products were observed, probably because they are thermodynamically more stable than the Z-isomers. When the reaction of 2a with 11a was conducted using (Q)Rh{P(pMeOC6H4)3}2 (15a), prepared by the reaction of 12 with 13a, as a catalyst, enamine 14aa was obtained in 62% yield. This result suggests that the COD ligand in 12 was exchanged with 13a under the reaction conditions.


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ACS Catalysis

Because it was suggested that a phosphine ligand is essential to achieve high efficiency in the 8quinolinolato-rhodium-catalyzed hydroamination, we synthesized rhodium(I) complexes bearing a tridentate ligand containing both a phosphine and an 8-quinolinolate moieties (abbreviated to PNO). The reaction of [Rh(OMe)(cod)]2 (16) with a tridentate phosphine-quinolinol 17 in benzene at room temperature afforded dinuclear rhodium(I) complex 18 in 61% yield (eq 5).30 Complex 18 can be used as a precursor for synthesis of (PNO)Rh(L) complexes (19) having various monodentate ligand (L) (Scheme 1). Generation of dinuclear complex 18 in situ by reacting 16 with 17 at room temperature, followed by treatment with phosphine 13a afforded (PNO)Rh(P(4MeOC6H4)3) (19a) in 89% yield. Other (PNO)Rh(L) complexes (19b-e) were similarly synthesized in 25-98% yields by the reaction of in-situ generated 18 with PPh3 (13b), P(4CF3C6H4)3 (13c), pyridine, and CO.


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Scheme 1. Synthesis of (Q)Rh(L) Complexes

Examination of the 8-quinolinolato rhodium complexes as catalysts for the hydroamination showed that the complex having -accepting CO ligand, 19e, catalyzed the addition of 11a to 1octyne (2h) with higher activity than 18 and 19a (eq 6). Both aliphatic (2h) and aromatic (2a,i) terminal alkynes are applicable to the hydroamination catalyzed by 19e.


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In order to gain insight into the reaction mechanism, the reactivity of the (PNO)Rh complexes toward the substrates were examined using a stoichiometric amount of (PNO)Rh dimer complex 18. The reaction of in-situ-generated 18 with 1-octyne (2h) gave vinylidene-bridged dirhodium complex 21h, which is considered to be generated via nucleophilic attack of mononuclear (PNO)Rh complex 22 to the carbene carbon in the vinylidene ligand of 20h (eq 7). The similar reactions with ferrocenylacetylene (2i), cyclohexylacetylene (2j), 3-cyclohexyl-1-propyne (2k), and tert-butyl acetylene (2l) also afforded the corresponding vinylidene-bridged dirhodium complexes 21i-l in 33, 78, 82, and 74% yields, respectively. The structures of complexes 21 were determined by various NMR spectra. Single crystal X-ray diffraction analysis was also conducted for complex 21i to show that the obtained structure was consistent with the results of the NMR analysis. The bridging-vinylidene ligand can exchange with a free terminal alkyne in the presence of pyridine or 4-N,N-dimethylaminopyridine (DMAP).


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The reactions of complex 21h with piperidine (11a) and isoindoline (11d) at 90 °C for 24 h afforded (PNO)Rh(aminocarbene) complexes 23ha and 23hd in 88 and 82% yields, respectively (eq 8). The structure of 23hd was confirmed by a single-crystal X-ray diffraction analysis. The 13

C{1H} NMR spectrum of 23hd showed a signal corresponding to a carbene carbon coupled with

a rhodium and a phosphorus nuclei at 263.6 ppm (dd, J = 43.2, 13.5 Hz) as is consistent with its solid state structure.


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Simple heating of in-situ-generated (PNO)Rh(aminocarbene) complex 23ha provided hydroamination product 14ha only in a low yield, but the use of additives facilitated the formation of 14ha. Particularly, the addition of ligands with good π-accepting character such as CO, P(4CF3C6H4)3 (13c), P(3,5-(CF3)2C6H3)3 (13d), and P(OPh)3 (13e) effectively accelerated the generation of 14ha (eq 9).

Figure 3 shows the proposed mechanism of the (PNO)Rh-catalyzed hydroamination based on results of stoichiometric reactions in addition to monitoring of the catalytic reactions. The reaction of 18 or/and 19 with alkyne 2 yields alkyne complex 24, which subsequently isomerizes to mononuclear vinylidene rhodium complex 20. Complex 20 reacts with 22 to give vinylidenebridged dirhodium complex 21. The reaction of 21 with amine 11 provides aminocarbene complex 23 via mononuclear complex 20. The reaction of 23 with a ligand (L) such as triarylphosphines leads to the formation of hydroamination product 14 with regenerating catalytically-active (PNO)Rh(L) species 18 or/and 19. The formation of hydroamination product 14 from aminocarbene complex 23 is considered to be rate-determining in this reaction. Many types of


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anti-Markovnikov addition reactions have been considered to proceed via formation of vinylidene intermediates, followed by nucleophilic attack, direct evidence of the presence of vinylidene intermediates and their adduct with nucleophiles were not shown in most cases.31 The experimental results obtained using (PNO)Rh complexes were the first structural determination of both of vinylidene and aminocarbene intermediates in catalytic hydroamination reactions.

Figure 3. Proposed Mechanism of (PNO)Rh(L)-Catalyzed anti-Markovnikov Hydroamination of Terminal Alkynes with Secondary Amines


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ACS Catalysis

Oro and co-workers have also studied the anti-Markovnikov hydroamination of terminal alkynes catalyzed by in-situ-generated 15a using [Rh(OMe)(cod)]2 (16), 8-quinolinol (H-Q), and P(4MeOC6H4)3 (13a).32 When the reaction of 2a with 11a was carried out using in-situ-generated 15a at room temperature for 24 h, the corresponding anti-Markovnikov hydroamination product 14aa was obtained in 51% yield (eq 10).

2.3. Synthesis of -Monosubstituted Propargylamines from Terminal Alkynes and Secondary Amines Using a (PNO)Rh(L)/CuBr Tandem Catalyst System While studying (PNO)Rh(L)-catalyzed hydroamination of terminal alkynes with secondary amines, we found that propargylamines were formed from two molecules of a terminal alkyne and one molecule of a secondary amine in the presence of CuBr. When the reaction of 1-octyne (2h) with piperidine (11a) was conducted using (PNO)Rh(PPh3) (19b) and CuBr as catalysts in toluene at 100 °C for 2 h, a 2:1 coupling reaction of 2h and 11a proceeded to give propargylamine 25ha in 89% yield (eq 11).33 Various functional groups such as ether and ester groups tolerated the reaction conditions. The stoichiometric reaction of (PNO)Rh(aminocarbene) complex 23ha with P(4-CF3C6H4)3 (13c) afforded enamine 14ha, which was detected by 1H NMR spectrum. Subsequently, CuBr, alkyne 2h, and Et3N were added to the reaction mixture containing enamine 14ha and heating of the resulting mixture at 90 °C for 2 days yielded propargylamine 25ha in 43% yield (eq 12). Based on these observations, the 2:1 coupling reaction is considered to proceed via


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two steps: (PNO)Rh(PPh3)-catalyzed anti-Markovnikov hydroamination of terminal alkyne 2 with secondary amine 11 to generate enamine 14 and formation of propargylamine 25 by the reaction of 14 with a copper acetylide species generated in situ from CuBr, alkyne 2, and triethylamine (Figure 4).


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Figure 4. Proposed Mechanism of the Formation of Propargylamines from Terminal Alkynes and Secondary Amines by the 19b/CuBr Tandem Catalyst System.

2.4. Synthesis of Alkenyl Aryl Sulfides by Markovnikov Addition of Thiols to Terminal Alkynes Castarlenas and co-workers reported on the alkyne hydrothiolation catalyzed by 8-quinolinolato rhodium complexes bearing an NHC ligand. The reaction of [Rh(-OH)(IPr)(coe)]2 (26) with 8quinolinol such as H-Q and 2-methyl-8-quinolinol at room temperature gave 8-quinolinolato rhodium complexes, (Q)Rh(IPr)(coe) (27) and (2-Me-Q)Rh(IPr)(coe) (28) (eq 13).34 These NHC complexes were catalytically active for the hydrothiolation of 2a with thiophenol. In the presence of pyridine additive, Markovnikov addition product 29 was obtained with high selectivity (97% selectivity) along with a small amount of anti-Markovnikov addition product 30 (eq 14). Studies of the reaction mechanism by NMR experiments and DFT calculations suggested that the


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hydrothiolation took place via oxidative addition of PhS–H bond to the rhodium(I) center to give a rhodium(III) hydride complex, and 2,1-insertion of 2a to the Rh–H bond, followed by reductive elimination provided the C–S bond formation product (Figure 5). The authors proposed that selective coordination of pyridine to the -alkenyl rhodium complex rather than sterically more hindered α-alkenyl rhodium complex retarded the reductive elimination from the β-alkenyl complex and led to the selective product formation from the α-alkenyl complex.


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ACS Catalysis

Figure 5. Proposed Mechanism of the (Q)Rh(IPr)-Catalyzed Hydrothiolation of Phenylacetylene (2a)

3. Alkyne Oligomerization/Polymerizations, Alkyne/Alkene Cycloaddition, and Their Related Reactions 8-Quinolinolato rhodium complexes were found to exhibit catalytic activities for alkyne oligomerization/polymerization to give polymers, cyclotrimerization products, and head-to-head


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and head-to-tail dimers. The complexes can also catalyze an alkyne/alkene coupling reaction to form cyclobutene derivatives. In this section, 8-quinolinolato-rhodium-catalyzed alkyne oligomerization/polymerization, alkyne/alkene coupling, and their related reactions are discussed. Polymerization of 2a was achieved using in-situ-generated 8-quinolinolato rhodium complexes. The reaction of 2a using a catalyst generated from [Rh(OMe)(nbd)]2 with 8-quinolinol (H-Q) led to complete conversion to polyphenylacetylene 31 with a high molecular weight (Mw = 167000, Mw/Mn 2.10) (eq 15).32

When the reaction of 2a in EtOH was carried out at 60-70 °C using (Q)Rh(CO)(coe) (32a) as a catalyst, 1,2,4-triphenylbenzenes (33a) was formed in 29.1% yield (eq 16).35 The use of (Q)Rh(CO)(AsPh3) (32b) as a catalyst afforded 1,2,4- and 1,3,5-triphenylbenzenes (33a and 33b) in 43.1 and 10.3% yields, respectively. 8-Quinolinolato complex 32a showed higher catalytic activity in the alkyne trimerization reaction than structurally-similar (acac)Rh(CO)(coe), and provided only a trace amount of 33.


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The additional ligand of 8-quinolinolato rhodium complexes, (Q)Rh(L), largely affected catalytic properties. When (Q)Rh(cod) (12) and (4-MeOC6H4)3P (13a) were used as catalysts for the reaction of 2a in toluene-d8 at 60 °C for 4 h, head-to-tail dimer 34 and head-to-head dimer 35 were obtained in 56 and 8% yields, respectively (eq 17).36 This result is in sharp contrast with the reaction described in equation 16, as the use of CO and AsPh3 ligands led to the formation of trimer 33. While various catalyst systems have been developed to form head-to-head dimers of terminal alkynes,37 few studies of selective head-to-tail dimerization have been reported.38 The catalyst system consisting of 12 and 13a is useful for the synthesis of unstable head-to-tail dimers of arylacetylenes.

When the alkyne dimerization was carried out in the presence of dimethyl malonate, cyclopentene derivative 36a was formed by 2:1 coupling of 2a and dimethyl malonate and obtained in 35% yield (eq 18).36 The reactions with several arylacetylenes afforded the


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corresponding 2:1 cycloaddition products, albeit in moderate yields. The 2:1 coupling reaction using dimethyl methylmalonate afforded allene-containing product 37, which was formed by rhodium-catalyzed nucleophilic attack of dimethyl methylmalonate to 34, generated in situ by head-to-tail dimerization of 2a (eq 19).

8-Quinolinolato rhodium complexes can also catalyze the [2 + 2] cycloaddition of terminal alkynes with electron-deficient alkenes.39 The reaction of n-butyl acrylate with 3 equiv of 1-octyne (2h) using a 12/13c/CsF catalyst system in DMA at 80 °C selectively gave butyl 3-hexyl-2cyclobutenecarboxylate (39ha) in 99% isolated yield (eq 20). Various aliphatic terminal alkynes having cyclohexyl, ester, cyano, and ether groups were applicable to the [2+2] cycloaddition, and in all cases the reaction afforded the corresponding cyclobutenes with complete regioselectivity. Other electron-deficient alkenes such as isopropyl and tert-butyl acrylates and acrylonitrile (38bd, respectively) reacted with 1-octyne to give the corresponding cyclobutenes 39hb-hd in 28-99% yields. 24 Environment ACS Paragon Plus

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Arylacetylenes can also be applied to the [2 + 2] cycloaddition reaction, but their reactivity is different from aliphatic alkynes. When the reaction of alkyne 2f with n-butyl acrylate (38a) (3 equiv) was conducted under the standard reaction conditions, cyclobutene 39fa was obtained in 24% yield along with 1:2 addition product 40 in 28% yield (eq 21). Extension of the reaction time to 48 h increased the yield of 40 to 42% and decreased the yield of 39fa to 3%. Therefore, 1:2 addition product 40 is considered to be formed by 1,4-addition of 39fa to another molecule of acrylate 38a.


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Our group proposed the catalytic cycle of the [2 + 2] cycloaddition in the original paper,39 and Fang and co-workers investigated the reaction mechanism further by DFT calculation to suggest the mechanism shown in Figure 6.40 Coordination of fluoride to the rhodium center, followed by dissociation of COD generates catalytically active species 41, in which F- weakly interacts with Cs+ and binds to the coordination site trans to the quinoline nitrogen (12 → 41). The alkyne coordinates to the rhodium center (41 → 42) and deprotonation at the terminal position gives alkynylrhodium intermediate 43. Nucleophilic attack of the β-carbon of the alkynyl ligand onto the β-carbon of the acylate produces rhodium vinylidene intermediate 44. Cyclization by nucleophilic attack of the -carbon of the acrylate to the vinylidene ligand led to the formation of cyclobutenyl intermediate 45. Protonation of the Rh–C bond (45 → 46) and dissociation of cyclobutene 39ha from the rhodium center regenerates the catalytically active species 41. The theoretical studies indicate that the electron-withdrawing groups such as ester and cyano groups stabilize the anionic character of the -carbon in intermediate 44 and the cyclization process is the rate-determining step.


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Figure 6. Proposed Mechanism of the Formation of Cyclobutenes from Terminal Alkyne and Acrylates by the (Q)Rh(cod)/phosphine/CsF catalyst system Based on the DFT Calculation.


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4. CONCLUSION AND OUTLOOK In this Perspective, we briefly surveyed catalytic reactions of terminal alkynes using rhodium(I) complexes having 8-quinolinolates, which can be regarded as monoanionic, hard, strongly σdonating ligands. Unique features of 8-quinolinolate ligands and catalytic activities of rhodium(I) complexes bearing these ligands were discussed. Reaction developments using mismatched soft metal/hard ligand catalyst system have not been pursued extensively, but several characteristic features have been revealed for the 8-quinolinolato rhodium catalysts as described in this perspective. The oxygen in the quinolinolate ligands is considered to function as a coordinating group as well as a base in the hydroalkoxylation of terminal alkynes. In addition, the phenoxide oxygen was suggested to weakly interact with cesium cation in the [2 + 2] cycloaddition of terminal alkynes with acrylates. These features may become useful to the design of the catalytic reactions using 8quinolinolato transition metal complexes. Installation of a phosphine moiety on the quinolinolate framework facilitated isolations and observations of key intermediates in the catalytic alkyne hydroamination, such as vinylidene-bridged dirhodium and (aminocarbene)rhodium complexes, and reversibility of the vinylidene formation was also suggested by the stoichiometric reaction using (PNO)Rh(L) complexes. These findings may provide valuable information for future studies of transition-metal-catalyzed anti-Markovnikov addition to terminal alkynes. The chemistry of 8-quinolinolato rhodium catalysts toward terminal alkynes described in this Perspective is just an example of the fields explored by mismatched soft metal/hard ligand catalyst systems, and a variety of reactions have been discovered by unique combinations of metals and


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ligands as catalysts. We believe that further exploration of the use of hard ligands in soft metal catalysis will lead to developments of unprecedented organic reactions.


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AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] ORCID Fumitoshi Kakiuchi: 0000-0003-2605-4675 Takuya Kochi: 0000-0002-5491-0566

Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

ACKNOWLEDGMENT The authors acknowledge financial support by a Grant-in-Aid for Scientific Research (B) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (16H04150 and 24350050). T.K. is also grateful for support by JSPS KAKENHI Grant Number 18H04271 (Precisely Designed Catalysts with Customized Scaffolding).

REFERENCES


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1.

(a) Transition Metals in the Synthesis of Complex Organic Molecules, 3rd ed.; Hegedus, L. S., Söderberg, B. C. G., Eds.; University Science: California, 2010. (b) Organotransition Metal Chemistry: From Bonding to Catalysis; Hartwig, J. F., Ed.; University Science: California, 2010. (c) Applied Homogeneous Catalysis; Behr, A.; Neubert, P., Eds.; Weily-VCH Verlag, Weinheim, 2012. (d) Catalytic Asymmetric Synthesis, 3rd ed.; Ojima, I., Ed.; Weiley, New Jersey, 2010. (e) Applied Homogeneous Catalysis with Organometallic Compounds, 3rd ed.; Cornils, B., Herrmann, W. A., Beller, M., Paciello, R., Eds.; Wiley-VCH Verlag GmbH: Weinheim, 2018.

2.

(a) Ligand Platforms in Homogeneous Catalytic Reactions with Metals; Yamaguchi, R., Fujita, K.-I., Eds.; Weily, New Jersey, 2015. (b) Catalysis, 2nd ed.; Rothenberg, G., Ed.; Weily-VCH Verlag GmbH: Weinheim, 2017.

3.

For Al complexes, see: (a) Khan, R. U. A.; Kwon, O-P.; Tapponnier, A.; Rashid, A. N.; Günter, P. Supramolecular Ordered Organic Thin Films for Nonlinear Optical and Optoelectronic Applications. Adv. Funct. Mater. 2006, 16, 180-188. (b) Murphy, L.; Williams, J. A. G. Luminescent Platinum Compounds: From Molecules to OLEDs. Top. Organomet. Chem. 2010, 28(Molecular Organometallic Materials for Optics), 75-111.

4.

For Cu complexes, see: (a) Nicholas, D. D.; Henry, W. P.; Vasishth, R. C. The Role of Copper in Wood Preservation. In Handbook of Copper Compounds and Applications; Richardson, H. W., Ed.; Marcel Dekker: New York, 1997; pp 163-176. (b) Kamdem, D. P. Copper-based Synthesis for Exterior Residential Applications. In Development of Commercial Wood Preservatives; Schultz, T. P., Holger, M., Michael, H. F., Goodell, B., Nicholas, D. D., Eds; ACS Symposium Series 982; American Chemical Society: Washington, DC, 2008; pp 427439.


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5.

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For Fe complexes, see: (a) Vogler, A. Intraligand fluorescence of M(III)(oxinate)3 under ambient conditions with M = Fe, Ru, Os and oxinate = 8-quinolinolate. Inorg. Chem. Commun. 2017, 84, 131-133. (b) Al-Noor, T. H.; Karam, N. H.; Ghanim, F. H.; Kindeel, A. S.; AlDujaili, A. H. Synthesis, characterization and liquid crystalline properties of novel benzimidazol-8-hydroxyquinoline complexes. Inorg. Chim. Acta 2017, 466, 612-617.

6.

For Co complexes, see: Abu-Hussen, A. A. A. Synthesis and spectroscopic studies on ternary bis-Schiff-base complexes having oxygen and/or nitrogen donors. J. Coord. Chem. 2006, 59, 157-176.

7.

(a) Ugo, R.; La Monica, G.; Cenini, S.; Bonati, F. Rhodium(I) and iridium(I) carbonyl derivatives with anionic chelating ligands. J. Organomet. Chem. 1968, 11, 159-166. (b) Varshavskii, Yu. S.; Knyazeva, N. N.; Cherkasova, T. G.; Ivannikova, N. V.; Ionina, T. I. Reaction of the product of rhodium carbonylation by dimethylformamide with 8hydroxyquinoline and 8-mercaptoquinoline. Zh. Neorg. Khim. 1970, 15, 715-722. (c) Varshavskii, Yu. S.; Cherkasova, T. G.; Buzina, N. A.; Knyazeva, N. N.; Ionina, T. I. Analogs of β-diketonatedicarbonyl derivatives of rhodium(I). Zh. Neorg. Khim. 1970, 15, 2294-2296. (d) Varshavsky, Ju. S.; Kiseleva, N. V.; Cherkasova, T. G.; Buzina, N. A. Dimethylformamide carbonylation of platinum group metals under mild homogeneous conditions. Reactions of carbonyl-containing complexes. J. Organomet. Chem. 1971, 31, 119-122. (e) Kuz'mina, L. G.; Varshavskii, Yu. S.; Bokii, N. G.; Struchkov, Yu. T.; Cherkasova, T. G. Crystal structure of

8-hydroxyquinolinato(triphenyl-phosphine)rhodium

carbonyl

and

8-

hydroxyquinolinatorhodium dicarbonyl. Zh. Strukt. Khim. 1971, 12, 653-660. (f) Varshavskii, Yu, S.; Cherkasova, T. G.; Buzina, N. A. Action of halogens on rhodium(I) carbonyl complexes containing bidentate singly charged ligands. Zh. Neorg. Kim. 1972, 17, 2208-2214.


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(g) Varshavsky, Yu. S.; Cherkasova, T. G.; Buzina, N. A.; Kormer, V. A. Mixed carbonyl cyclooctene complexes of rhodium(I). cis-cyclooctene as ligand. J. Organomet. Chem. 1974, 77, 107-115. (h) Gillard, R. D.; Harrison, K.; Mather, I. H. 1,10-Phenanthroline Complexes of Rhodium(I). J. Chem. Soc., Dalton Trans. 1975, 0, 133-140. (i) Goswami, K.; Singh, M. M. Di and Monocarbonyl Complexes of Rhodium(I) containing Singly Charged Bidentate Ligands. Transition Met. Chem. 1980, 5, 83-85. (j) Usón, R.; Oro, L. A.; Sanaú, M.; Lahuerta, P.; Hildenbrand, K. Organometallic complexes of Rh(I) with the group 5-methyl oxyquinolate. J. Inorg. Nucl. Chem. 1981, 43, 419-421. (k) Leipoldt, J. G.; Basson, S. S.; Dennis, C. R. The Crystal Structure of 8-Hydroxyquinolinatocarbonyltriphenylphosphinerhodium(I). Inorg. Chim. Acta. 1981, 50, 121-124. (l) Leipoldt, J. G.; Grobler, E. C. The Crystal Structure of 8Hydroxyquinolinato(1,5-cyclooctadiene)rhodium(I). Inorg. Chim. Acta. 1983, 72, 17-20. (m) Barceló, F. L.; Besteiro, J. C.; Lahuerta, P.; Foces-Foces, C.; Cano, F. H.; Martínez-Ripoll, M. Cyclometallation reactions in complexes of the type Rh(oq)(CO)[P(o-BrC6F4)Ph2]. The molecular structure of Rh(oq)2[P(o-C6F4)Ph2] (oq = 8-hydroxyquinolinate). J. Organomet. Chem. 1984, 270, 343-351. (n) Lahuerta, P.; Sanau, M.; Oro, L. A.; Carmona, D. Preparation and Oxidative Addition Reactions of 8-Oxyquinolate Rhodium(I) Complexes. Synth. React. Inorg. Met.-Org. Chem. 1986, 16, 301-325. (o) Wajda-Hermanowicz, K.; Pruchnik, F. P. Carbonylrhodium

complexes

with

pyridylphosphines:

[Rh(chel)(CO)(PPhXpyl3-X)].

Transition Met. Chem. 1988, 13, 22-24. (p) Chen, W.; Xu, Y.; Liao, S. Synthesis and catalytic properties of rhodium(I) complexes with anionic chelate nitrogen-oxygen ligands. Transition Met. Chem. 1994, 19, 418-420. (q) Simanko, W.; Mereiter, K.; Schmid, R.; Kirchner, K.; Trzeciak, A. M.; Ziołkowski, J. J. Rh(acac)(CO)(PR3) and Rh(oxinate)(CO)(PR3) complexes– substitution chemistry and structural aspects. J. Organomet. Chem. 2000, 602, 59-64. (r)


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Varshavsky, Yu. S.; Galding, M. R.; Cherkasova, T. G.; Smirnov, S. N.; Khrustalev, V. N. First examples of [Rh(Bident)(CO)(L)] complexes where L is N-donor ligand: Molecular structure of [Rh(8-Oxiquinolinato)(CO)(NH3)]. J. Organomet. Chem. 2007, 692, 5788-5794. (s) Varshavsky, Yu. S.; Galding, M. R.; Khrustalev, V. N.; Podkorytov, I. S.; Smirnov, S. N.; Gindin, V. A.; Nikolskii, A. B. Rhodium(I) dimethyl sulfoxide oxyquinolinato carbonyl complex, [Rh(Oxq)(CO)(DMSO)]. NMR and X-ray structure data. J. Organomet. Chem. 2014, 761, 123-126. 8.

(a) Usón, R.; Oro, L. A.; Ciriano, M. A.; Gonzalez, R. 8-Oxyquinolate iridium(I) complexes and their oxidative-addition reactions. J. Organomet. Chem. 1981, 205, 259-271. (b) Usón, R.; Oro, L. A.; Carmona, D.; Esteruelas, M. A. Iridium(I) complexes with tetrafluorobenzobarrelene. J. Organomet. Chem. 1984, 263, 109-120. (c) Rampersadh, T.; Fernandes, M. A.; Carlton, L. Iridium Complexes of Aromatic N,O and N,N Chelating Ligands. Structures

of

[Ir(8OQ)(cod)],

[Ir(8OQd)(cod)],

[Ir2(7AI)2(cod)2]

and

[Ir(8OQd)(H)(EPh3)(cod)] (8OQ = 8-Oxyquinolinate, 8OQd = 2-Methyl-8-oxyquinolinate, 7AI = 7-Azaindolate; E = Si, Sn; cod = 1,5-Cyclooctadiene). J. Chem. Crystallogr. 2014, 44, 151-160. 9.

(a) Di Giuseppe, A.; Castarlenas, R.; Pérez-Torrente, J. J.; Lahoz, F. J.; Polo, V.; Oro, L. A. Mild and Selective H/D Exchange at the β Position of Aromatic α-Olefins by N-Heterocyclic Carbene-Hydride-Rhodium Catalysts. Angew. Chem., Int. Ed. 2011, 50, 3938-3942. (b) Di Giuseppe, A.; Castarlenas, R.; Pérez-Torrente, J. J.; Lahoz, F. J.; Oro, L. A. HydrideRhodium(III)-N-Heterocyclic Carbene Catalysts for Vinyl-Selective H/D Exchange: A Structure-Activity Study. Chem. Eur. J. 2014, 20, 8391-8403.


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10. Trach, Yu. B.; Makota, O. I.; Cherkasova, T. G.; Gal’ding, M. R.; Varshavskii, Yu. S. Catalytic Properties of Rhodium Organometallic Complexes in the Reaction of 1-Octene Oxidation with Molecular Oxygen. Russ. J. Gen. Chem. 2010, 80, 1208-1209. 11. (a) Janecko, H.; Trzeciak, A. M.; Ziółkowski, J. J. New rhodium complexes as low pressure hydroformylation catalysts: effect of ligand on catalyst activity and selectivity. J. Mol. Catal. 1984, 26, 355-361. (b) Chen, W.; Liao, S.; Xu, Y. Effect of Phosphorus Ligands on the Hydroformylation of Olefins over Rhodium Catalysts under Atmospheric Pressure. Heteroatom Chem. 1992, 3, 539-545. (c) Chen, W.; Xu, Y.; Liao, S. Synthesis and catalytic properties of rhodium(I) complexes with anionic chelate nitrogen-oxygen ligands. Transition Met. Chem. 1994, 19, 418-420. 12. (a) Hetterscheid, D. G. H.; Hendriksen, C.; Dzik, W. I.; Smits, J. M. M.; van Eck, E. R. H.; Rowan, A. E.; Busico, V.; Vacatello, M.; Castelli, V. V. A.; Segre, A.; Jellema, E.; Bloemberg, T. G.; de Bruin, B. Rhodium-Mediated Stereoselective Polymerization of “Carbenes”. J. Am. Chem. Soc. 2006, 128, 9746-9752. (b) Jellema, E.; Budzelaar, P. H. M.; Reek, J. N. H.; de Bruin, B. Rh-Mediated Polymerization of Carbenes: Mechanism and Stereoregulation. J. Am. Chem. Soc. 2007, 129, 11631-11641. 13. (a) Hintermann, L. Recent Developments in Metal-Catalyzed Additions of Oxygen Nucleophiles to Alkenes and Alkynes. Top. Organomet. Chem. 2010, 31 (C-X Bond Formation), 123-155. (b) Abbiati, G.; Beccalli, E. M.; Rossi, E. Group 9 and 10 MetalsCatalyzed O–H Bond Addition to Unsaturated Molecules. Top. Organomet. Chem. 2013, 43 (Hydrofunctionalization), 231-290. 14. Bruneau, C. Anti-Markovnikov Additions of O, N, P-Nucleophiles to Triple Bonds with Ruthenium Catalysts. In Metal Vinylidenes and Allenylidenes in Catalysis; Bruneau, C.,


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Dixneuf, P. H., Eds.; Wiley-VCH Verlag GmbH: Weinheim, 2008; pp 315-318. See also ref 13b. 15. (a) Schafer, L. L.; Yim, J. C.-H.; Yonson, N. Transition-Metal-Catalyzed Hydroamination Reactions. In Metal-Catalyzed Cross-Coupling Reactions and More; de Meijere, A., Bräse, S., Oestreich, M., Eds.; Wiley-VCH Verlag GmbH: Weinheim, 2014; Vol. 3, pp 1135-1258. (b) Nishina, N.; Yamamoto, Y. Late Transition Metal-Catalyzed Hydroamination. Top. Organomet. Chem. 2013, 43 (Hydrofunctionalization), 115-144. 16. Bichler, P.; Love, J. A. Organometallic Approaches to Carbon-Sulfur Bond Formation. Top. Organomet. Chem. 2010, 31(C-X Bond Formation), 39-64. 17. (a) Fischer, P. In The Chemistry of Functional Groups, Supplement E; Patai, P., Ed.; John Wiley & Sons: Chichester, 1980, Chapter 17. Recent uses of β-alkoxystyrenes: (b) Shimasaki, T.; Konno, Y.; Tobisu, M.; Chatani, N. Nickel-Catalyzed Cross-Coupling Reaction of Alkenyl Methyl Ethers with Aryl Boronic Esters. Org. Lett. 2009, 11, 4890-4892. (c) Whelligan, D. K.; Thomson, D. W.; Taylor, D.; Hoelder, S. Two-Step Synthesis of Aza- and Diazaindoles from Chloroamino-N-heterocycles Using Ethoxyvinylborolane. J. Org. Chem. 2010, 75, 1115. 18. Reppe, W. Vinylation. I. Vinyl ethers and vinyl esters. Liebigs Ann. Chem. 1956, 601, 84111. 19. Intramolecular hydroalkoxylation of alkynes: (a) McDonald, F. E. Alkynol endoCycloisomerizations and Conceptually Related Transformations. Chem. Eur. J. 1999, 5, 31033106. (b) Alonso, F.; Beletskaya, I. P.; Yus, M. Transition-Metal-Catalyzed Addition of Heteroatom-Hydrogen Bonds to Alkynes. Chem. Rev. 2004, 104, 3079-3159. (c) Trost, B. M.; McClory, A. Metal Vinylidenes as Catalytic Species in Organic Reactions. Chem. Asian J.


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2008, 3, 164-194. Selected recent examples: (d) Zacuto, M. J.; Tomita, D.; Pirzada, Z.; Xu, F. Chemoselectivity of the Ru-Catalyzed Cycloisomerization Reaction for the Synthesis of Dihydropyrans; Application to the Synthesis of L-Forosamine. Org. Lett. 2010, 12, 684-687. (e) Varela-Fernández, A.; García-Yebra, C.; Varela, J. A.; Esteruelas, M. A.; Saá, C. OsmiumCatalyzed 7-endo Heterocyclization of Aromatic Alkynols into Benzoxepines. Angew. Chem., Int. Ed. 2010, 49, 4278-4281. 20. Intermolecular hydroalkoxylation of alkynes: (a) Teles, J. H.; Brode, S.; Chabanas, M. Cationic Gold(I) Complexes: Highly Efficient Catalysts for the Addition of Alcohols to Alkynes. Angew. Chem., Int. Ed. 1998, 37, 1415-1418. (b) Breuer, K.; Teles, J. H.; Demuth, D.; Hibst, H.; Schäfer, A.; Brode, S.; Domgörgen, H. Zinc Silicates: Very Efficient Heterogeneous Catalysts for the Addition of Primary Alcohols to Alkynes and Allenes. Angew. Chem., Int. Ed. 1999, 38, 1401-1405. (c) Elgafi, S.; Field, L. D.; Messerle, B. A. Cyclisation of acetylenic carboxylic acids and acetylenic alcohols to oxygen-containing heterocycles using cationic rhodium(I) complexes. J. Organomet. Chem. 2000, 607, 97-104. (d) Casado, R.; Contel, M.; Laguna, M.; Romero, P.; Sanz, S. Organometallic Gold(III) Compounds as Catalysts for the Addition of Water and Methanol to Terminal Alkynes. J. Am. Chem. Soc. 2003, 125, 11925-11935. 21. (a) Murata, T.; Mizobe, Y.; Gao, H.; Ishii, Y.; Wakabayashi, T.; Nakano, F.; Tanase, T.; Yano, S.; Hidai, M.; Echizen, I.; Nanikawa, H.; Motomura, S. Syntheses of Mixed-Metal Sulfide Cubane-Type Clusters with the Novel PdMo3S4 Core and Reactivities of the Unique Tetrahedral Pd Site Surrounded by Sulfide Ligands toward Alkenes, CO, tBuNC, and Alkynes. J. Am. Chem. Soc. 1994, 116, 3389-3398. (b) Kataoka, Y.; Matsumoto, O.; Tani, K.


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Stereoselective Addition of Alcohol to Acetylenecarboxylate Catalyzed by Silver(I) Salt. Chem. Lett. 1996, 25, 727-728. 22. Gemel, C.; Trimmel, G.; Slugovc, C.; Kremel, S.; Mereiter, K.; Schmid, R.; Kirchner, K. Ruthenium

Tris(pyrazolyl)borate

Complexes.

1.

Synthesis

and

Reactivity

of

Ru(HB(pz)3)(COD)X (X = Cl, Br) and Ru(HB(pz)3)(L2)Cl (L = Nitrogen and Phosphorus Donor Ligands). Organometallics 1996, 15, 3998-4004. 23. Kondo, M; Kochi, T.; Kakiuchi, F. Rhodium-Catalyzed Anti-Markovnikov Intermolecular Hydroalkoxylation of Terminal Acetylenes. J. Am. Chem. Soc. 2011, 133, 32-34. 24. (a) Dang, Y.; Qu, S.; Wang, Z.-X.; Wang, X. Mechanism and Origins of Z Selectivity of the Catalytic Hydroalkoxylation of Alkynes via Rhodium Vinylidene Complexes To Produce Enol Ethers. Organometallics 2013, 32, 2804-2813. (b) Liu, Z.; Guo, J.; Song, C.; Hu, W.; Dang, Y.; Wang, Z.-X. The Origins of the Differences between Alkyne Hydroalkoxylations Catalyzed by 8-Quinolinolato- and Dipyrrinato-Ligated RhI Complexes: A DFT Mechanistic Study. Eur. J. Inorg. Chem. 2017, 2017, 2713-2722. 25. Lam, R. H.; Walker, D. B.; Tucker, M. H.; Gatus, M. R. D.; Bhadbhade, M.; Messerle, B. A. Intermolecular Hydroalkoxylation of Terminal Alkynes Catalyzed by a Dipyrrinato Rhodium(I) Complex with Unusual Selectivity. Organometallics 2015, 34, 4312-4317. 26. Reviews on hydroamination of alkynes: (a) Beller, M.; Breindl, C.; Eichberger, M.; Hartung, C. G.; Seayad, J.; Thiel, O. R.; Tillack, A.; Trauthwein, H. Advances and Adventures in Amination Reactions of Olefins and Alkynes. Synlett 2002, 1579-1594. (b) Pohlki, F.; Doye, S. The catalytic hydroamination of alkynes. Chem. Soc. Rev. 2003, 32, 104-114. (c) Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Catalytic Markovnikov and anti-Markovnikov Functionalization of Alkenes and Alkynes: Recent Developments and Trends. Angew. Chem.,


Page 39 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis

Int. Ed. 2004, 43, 3368-3398. (d) Hong, S.; Marks, T. J. Organolanthanide-Catalyzed Hydroamination. Acc. Chem. Res. 2004, 37, 673-686. (e) Beller, M.; Tillack, A.; Seayad, J. Catalytic Amination Reactions of Olefins and Alkynes. In Transition Metals for Organic Synthesis, 2nd ed.; Beller, M., Bolm, C., Eds; Wiley-VCH: Weinheim, 2004; Vol.2, pp 403414. (f) Odom, A. L. New C-N and C-C bond forming reactions catalyzed by titanium complexes. Dalton Trans. 2005, 0, 225-233. (g) Severin, R.; Doye, S. The catalytic hydroamination of alkynes. Chem. Soc. Rev. 2007, 36, 1407-1420. (h) Aillaud, I.; Collin, J.; Hannedouche, J.; Schulz, E. Asymmetric hydroamination of non-activated carbon–carbon multiple bonds. Dalton Trans. 2007, 0, 5105-5118. (i) Müller, T. E.; Hultzsch, K. C.; Yus, M.; Foubelo, F.; Tada, M. Hydroamination: Direct Addition of Amines to Alkenes and Alkynes. Chem. Rev. 2008, 108, 3795-3892. (j) Fukumoto, Y. Catalytic Hydroamination of C-C Multiple Bonds. J. Synth. Org. Chem. Jpn. 2009, 67, 735-750. 27. (a) Haskel, A.; Straub, T.; Eisen, M. S. Organoactinide-Catalyzed Intermolecular Hydroamination of Terminal Alkynes. Organometallics 1996, 15, 3773-3775. (b) Haak, E.; Siebeneicher, H.; Doye, S. An Ammonia Equivalent for the Dimethyltitanocene-Catalyzed Intermolecular Hydroamination of Alkynes. Org. Lett. 2000, 2, 1935-1937. (c) Tillack, A.; Garcia Castro, I.; Hartung, C. G.; Beller, M. Anti-Markovnikov Hydroamination of Terminal Alkynes. Angew. Chem., Int. Ed. 2002, 41, 2541-2543. (d) Tillack, A.; Jiao, H.; Garcia Castro, I.; Hartung, C. G.; Beller, M. A General Study of [(η5-Cp’)2Ti(η2-Me3SiC2SiMe3)]-Catalyzed Hydroamination of Terminal Alkynes: Regioselective Formation of Markovnikov and AntiMarkovnikov Products and Mechanistic Explanation (Cp’ = C5H5, C5H4Et, C5Me5). Chem. Eur. J. 2004, 10, 2409-2420. (e) Fukumoto, Y.; Asai, H.; Shimizu, M.; Chatani, N. AntiMarkovnikov Addition of Both Primary and Secondary Amines to Terminal Alkynes


ACS Catalysis 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 40 of 45

Catalyzed by the TpRh(C2H4)2/PPh3 System. J. Am. Chem. Soc. 2007, 129, 13792-13793. (f) Alonso-Moreno, C.; Carrillo-Hermosilla, F.; Romero-Fernández, J.; Rodríguez, A. M.; Otero, A.; Antiñolo, A. Well-Defined Regioselective Iminopyridine Rhodium Catalysts for AntiMarkovnikov Addition of Aromatic Primary Amines to 1-Octyne. Adv. Synth. Catal. 2009, 351,

881-890.

(g)

Brahms,

C.;

Tholen,

P.;

Saak,

W.;

Doye,

S.

An

(Aminopyrimidinato)titanium Catalyst for the Hydroamination of Alkynes and Alkenes. Eur. J. Org. Chem. 2013, 2013, 7583-7592. (h) Yim, J. C.-H.; Bexrud, J. A.; Ayinla, R. O.; Leitch, D. C.; Schafer, L. L. Bis(amidate)bis(amido) Titanium Complex: A Regioselective Intermolecular Alkyne Hydroamination Catalyst. J. Org. Chem. 2014, 79, 2015-2028. 28. Transition-metal-catalyzed anti-Markovnikov addition of secondary amines to terminal alkynes: (a) Leitch, D. C.; Payne, P. R.; Dunbar, C. R.; Schafer, L. L. Broadening the Scope of Group 4 Hydroamination Catalysis Using a Tethered Ureate Ligand. J. Am. Chem. Soc. 2009, 131, 18246-18247. (b) Leitch, D. C.; Turner, C. S.; Schafer, L. L. Isolation of Catalytic Intermediates in Hydroamination Reactions: Insertion of Internal Alkynes into a ZirconiumAmido Bond. Angew. Chem., Int. Ed. 2010, 49, 6382-6386. (c) Cheung, H. W.; So, C. M.; Pun,

K.

H.;

Zhou,

Z.;

Lau,

C.

P.

Hydro(trispyrazolyl)borato-Ruthenium(II)

Diphosphinoamino Complex-Catalyzed Addition of β-Diketones to 1-Alkynes and AntiMarkovnikov Addition of Secondary Amines to Aromatic 1-Alkynes. Adv. Synth. Catal. 2011, 353, 411-425. Catalytic Markovnikov addition of secondary amines to terminal alkynes: (a) Barluenga, J.; Aznar, F.; Liz, R.; Rodes, R. Catalytic and noncatalytic addition of aromatic amines to terminal acetylenes in the presence of mercury(II) chloride and acetate. J. Chem. Soc., Perkin Trans. 1 1980, 2732-2737. (b) Uchimaru, Y. N-H activation vs. C-H activation: ruthenium-catalysed regioselective hydroamination of alkynes and hydroarylation of an


Page 41 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis

alkene with N-methylaniline. Chem. Commun. 1999, 0, 1133-1134. (c) Zeng, X.; Frey, G. D.; Kousar, S.; Bertrand, G. A Cationic Gold(I) Complex as a General Catalyst for the Intermolecular Hydroamination of Alkynes: Application to the One-Pot Synthesis of Allenes from Two Alkynes and a Sacrificial Amine. Chem. Eur. J. 2009, 15, 3056-3060. Catalytic addition of secondary amines to internal alkynes: (a) Zeng, X.; Frey, G. D.; Kinjo, R.; Donnadieu, B.; Bertrand, G. Synthesis of a Simplified Version of Stable Bulky and Rigid Cyclic (Alkyl)(amino)carbenes, and Catalytic Activity of the Ensuing Gold(I) Complex in the Three-Component Preparation of 1,2-Dihydroquinoline Derivatives. J. Am. Chem. Soc. 2009, 131, 8690-8696. (b) Hesp, K. D.; Stradiotto, M. Stereo- and Regioselective Gold-Catalyzed Hydroamination of Internal Alkynes with Dialkylamines. J. Am. Chem. Soc. 2010, 132, 18026-18029. 29. Sakai, K.; Kochi, T.; Kakiuchi, F. Rhodium-Catalyzed anti-Markovnikov Addition of Secondary Amines to Arylacetylenes at Room Temperature. Org. Lett. 2011, 13, 3928-3931. 30. Takano, S.; Kochi, T.; Kakiuchi, F. Synthesis and Reactivity of Phosphine-Quinolinolato Rhodium Complexes: Intermediacy of Vinylidene and (Amino)carbene Complexes in the Catalytic Hydroamination of Terminal Alkynes. Organometallics 2016, 35, 4112-4125. 31. (a) Bruneau, C.; Dixneuf, P. H. Metal Vinylidenes in Catalysis. Acc. Chem. Res. 1999, 32, 311-323. (b) Fischmeister, C.; Bruneau, C.; Dixneuf, P. H. Nucleophilic Additions to Alkynes and Reactions via Vinylidene Intermediates. In Ruthenium in Organic Synthesis; Murahashi, S.–I., Ed.; WILEY-VCH Verlag GmbH & Co. KGaA: Weinheim, 2004; pp 189-217. (c) Bruneau, C.; Dixneuf, P. H. Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti-Markovnikov Additions to Terminal Alkynes and Alkene Metathesis. Angew. Chem., Int. Ed. 2006, 45, 2176-2203. (d) Wiedemann, S. H.; Lee, C. Rhodium and Group 9-11 Metal


ACS Catalysis 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Vinylidene in Catalysis. In Metal Vinylidenes and Allenylidenes in Catalysis: From Reactivity to Applications in Synthesis; Bruneau, C., Dixneuf, P. H., Eds.; WILEY-VCH Verlag GmbH & Co. KGaA: Weinheim, 2008; pp 279-312. 32. Jaseer, E. A.; Casado, M. A.; Al-Saadi, A. A.; Oro, L. A. Intermolecular hydroamination versus stereoregular polymerization of phenylacetylene by rhodium catalysts based on N-O bidentate ligands. Inorg. Chem. Commun. 2014, 40, 78-81. 33. Takano, S.; Kochi, T.; Kakiuchi, F. Formation of α-Monosubstituted Propargylamines from Terminal Alkynes and Secondary Amines Using a (PNO)Rh/Cu Tandem Catalyst System. Chem. Lett. 2017, 46, 1620-1623. 34. Palacios, L.; Giuseppe, A. D.; Artigas, M. J.; Polo, V.; Lahoz, F. J.; Castarlenas, R.; PérezTorrente, J. J.; Oro, L. A. Mechanistic insight into the pyridine enhanced α-selectivity in alkyne hydrothiolation catalysed by quinolinolate-rhodium(I)-N-heterocyclic carbene complexes. Catal. Sci. Technol. 2016, 6, 8548-8561. 35. Shestakova, V. S.; Shestakov, G. K.; Yur’eva, L. P.; Belyi, A. A.; Temkin, O. N. Cyclotrimerization of monosubstituted alkynes in the presence of rhodium, molybdenum, and tungsten complexes. Izv. Akad. Nauk SSSR, Ser. Khim. 1985, 534-536. 36. Mochizuki, K.; Sakai, K.; Kochi, T.; Kakiuchi, F. Rhodium-Catalyzed Dimerization of Arylacetylenes and Addition of Malonates to 1,3-Enynes. Synthesis 2013, 45, 2088-2092. 37. For examples of E-selective head-to-head dimerization, see: (a) Ogoshi, S.; Ueta, M.; Oka, M.-a.; Kurosawa, H. Dimerization of terminal alkynes catalyzed by a nickel complex having a bulky phosphine ligand. Chem. Comm. 2004, 0, 2732-2733. (b) Ciclosi, M.; Estevan, F.; Lahuerta, P.; Passarelli, V.; Pérez-Prieto, J.; Sanaú, M. An Unprecedented Iridium(III) Catalyst for Stereoselective Dimerisation of Terminal Alkynes. Adv. Synth. Catal. 2008, 350,


Page 42 of 45

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234–236. For a recent example of a Z-selective head-to-head dimerization, see: (c) Jahier, C.; Zatolochnaya, O. V.; Zvyagintsev, N. V.; Ananikov, V. P.; Gevorgyan, V. General and Selective Head-to-Head Dimerization of Terminal Alkynes Proceeding via Hydropalladation Pathway. Org. Lett. 2012, 14, 2846-2849. 38. (a) Trost, B. M.; Chan, C.; Ruhter, G. Metal-Mediated Approach to Enynes. J. Am. Chem. Soc. 1987, 109, 3486–3487. (b) Trost, B. M.; Sorum, M. T.; Chan, C.; Harms, A. E.; Rühter, G. Palladium-Catalyzed Additions of Terminal Alkynes to Acceptor Alkynes. J. Am. Chem. Soc. 1997, 119, 698–708. (c) Boese, W. T.; Goldman, A. S. Insertion of Acetylenes into CarbonHydrogen Bonds Catalyzed by Rhodium-Trimethylphosphine Complexes. Organometallics 1991, 10, 782–786. (d) Dash, A. K.; Eisen, M. S. Chemo- and Regioselective Dimerization of Terminal Alkynes Promoted by Methylaluminoxane. Org. Lett. 2000, 2, 737–740. (e) Baratta, W.; Herrmann, W. A.; Rigo, P.; Schwarz, J. Convenient syntheses of novel ruthenium catalysts bearing N-heterocyclic carbenes. J. Organomet. Chem. 2000, 593-594, 489–493. (f) Gao, Y.; Puddephatt, R. J. Selective head-to-tail dimerization of phenylacetylene catalyzed by a diruthenium μ-methylene complex. Inorg. Chim. Acta 2003, 350, 101–106. (g) Melis, K.; De Vos, D.; Jacobs, P.; Verpoort, F. Catalytic application of a Ru-alkylidene in the nucleophilic addition of several carboxylic acids on terminal alkynes and the homo-coupling of 1-alkynes. J. Organomet. Chem. 2003, 671, 131–136. (h) Lee, C.-C.; Lin, Y.-C.; Liu, Y.H.; Wang, Y. Rhodium-Catalyzed Dimerization of Terminal Alkynes Assisted by MeI. Organometallics 2005, 24, 136–143. (i) Peng, H. M.; Zhao, J.; Li, X. Synthesis of Trisubstituted Pyrroles from Rhodium-Catalyzed Alkyne Head-to-Tail Dimerization and Subsequent Gold-Catalyzed Cyclization. Adv. Synth. Catal. 2009, 351, 1371–1377. (j) Xu, H.D.; Zhang, R.-W.; Li, X.; Huang, S.; Tang, W.; Hu, W.-H. Rhodium-Catalyzed Chemo- and


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Regioselective Cross-Dimerization of Two Terminal Alkynes. Org. Lett. 2013, 15, 840-843. (k) Garcia-Garrido, S. E. Catalytic Dimerization of Alkynes. In Modern Alkyne Chemistry; Trost, B. M., Li, C.-J., Eds.; Wiley-VCH Verlag GmbH: Weinheim, 2015; pp 301-334. 39. Sakai, K.; Kochi, T.; Kakiuchi, F. Rhodium-Catalyzed Intermolecular [2 + 2] Cycloaddition of Terminal Alkynes with Electron-Deficient Alkenes. Org. Lett. 2013, 15, 1024-1027. 40. Zhao, L.; Zhang, L.; Fang, D.-C. DFT Study on Rhodium-Catalyzed Intermolecular [2 + 2] Cycloaddition of Terminal Alkynes with Electron-Deficient Alkenes. Organometallics 2016, 35, 3577-3586.


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