Article pubs.acs.org/Organometallics
N‑Heterocyclic Carbene C,S Palladium(II) π‑Allyl Complexes: Synthesis, Characterization, and Catalytic Application In Allylic Amination Reactions Deepa Krishnan, Meiyi Wu, Minyi Chiang, Yongxin Li, Pak-Hing Leung,* and Sumod A. Pullarkat* Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 S Supporting Information *
ABSTRACT: A series of five-membered N-heterocyclic carbene C,S palladium(II) π-allyl complexes were successfully developed and characterized. Structural analyses of these complexes revealed that the organopalladium chelates adopt a skew-envelope conformation with a trans disposition of the substituents on the metal chelate rings. Utilizing these C,S palladium(II) π-allyl complexes as catalysts, a catalytic system for the allylic amination reaction has been developed. A series of C−N bond formations between amines and unsymmetrically substituted allylic carbonates could be catalyzed efficiently by complex (±)-9 in a regioselective manner.
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INTRODUCTION The discovery of N-heterocyclic carbenes (NHCs) by Wanzlick1 and Ö fele2 in the 1960s focused significant attention on NHCs particularly as ancillary ligands in various transitionmetal-mediated catalytic reactions.3 The increased popularity of NHC ligands is attributed to the high inherent stability of these metal−carbene complexes to heat, moisture, and oxygen. Furthermore, their electronic and steric properties are easily tuned, which make NHCs a viable alternative to phosphines in various metal-based homogeneous catalytic reactions. The ease in the synthetic preparation of functionalized NHCs with a wide range of classical donors (E P,4 N,5 O6) provides an avenue for the construction of different polydentate ligands with unique coordination chemistry and their potential application in various metal-catalyzed reactions.7 In comparison with other donor-functionalized NHCs, the synthetic methodologies targeting sulfur-functionalized NHC metallacycle complexes are rare in the literature, although their potential in various catalytic scenarios such as C−C, C−O, and C−N bond formations have been demonstrated.8 Over the past few decades, transition metals such as Pd, Ni, Pt, Mo, W, Rh, and Ir have been successfully employed as catalysts in allylic substitution reactions.7f,9 However, Pdcatalyzed allylation via a π-allyl intermediate, through oxidative addition of allylic compounds, with successive nucleophilic attack at the allyl fragment yielding an active Pd0 species to afford the allylated product, is the widely used method for the construction of C−C, C−O, and C−N bonds in organic synthesis.3q,10 The formation of Pd0 species is generally achieved by the addition of activators, mostly phosphines, and consequently, a wide range of phosphine-based palladium complexes have been developed for allylic substitution reactions.11 Thus, our interest lies in the development of sulfur-functionalized NHC metallacycle complexes for the © 2013 American Chemical Society
phosphine-free allylic amination reaction, which to the best of our knowledge has not been reported to date. Although a few chelating NHC−Pd complexes (excluding sulfur donors) have been reported for the C−N bond formation reaction, these studies also highlight the inevitability of employing PPh3 to generate the active Pd0 species in their catalytic cycle.12 We herein report the synthesis of sulfur-functionalized NHC complexes of palladium, 9−12, that exhibit catalytic activity in the allylic amination reaction, most notably in the absence of any phosphine as additive. A detailed study of the role of the cationic π-allyl palladium(II) complexes and in particular (±)-9 in allylic amination was undertaken in this work.
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RESULTS AND DISCUSSION Synthesis and Characterization of Palladium(II) π-Allyl Complexes. The synthesis of palladium(II) π-allyl complexes 9−12 were accomplished via the transmetallation method13 (Scheme 1) with addition of 0.55 equiv of Ag2O to substituted thioether−imidazolium bromides 1−4 under the exclusion of light followed by the reaction of silver carbenes 5−8 with [Pd(η3−C3H5)(COD)]+BF4−. The complexation reactions proceeded smoothly to afford cationic palladium complexes 9−12 in 90−92% isolated yields. The complexes were isolated as white-gray powders and were fully characterized by NMR techniques (1H, 13C), mass spectrometry, and single-crystal X-ray crystallography. Structural Investigation of Palladium Complex 9. Colorless needlelike crystals of complex 9 were obtained by slow diffusion of diethyl ether into a dissolved diastereoisomer mixture of palladium(II) π-allyl complex 9 in acetone solution Received: February 8, 2013 Published: April 3, 2013 2389
dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
Organometallics
Article
Scheme 1. Synthesis of Palladium(II) π-Allyl Complexes
at −20 °C. The molecular structure of 9 was determined by single-crystal X-ray diffraction analysis. It is noteworthy that the parent complex may exist as a mixture of up to four diastereomers, as it contains one chiral carbon center and a coordinated sulfur stereogenic center. Interestingly, the crystal selected for analysis was that of one diastereomer, i.e., (RS,SC)*9, in its enantiomerically pure form (space group P212121, absolute structure parameter 0.00(6)). It is evident that in the solid state the five-membered palladacycle (RS,SC)*-9 adopts the λ(SC)-ring conformation where the phenyl substituent on the prochiral sulfur atom adopts the axial (Ph) position due to the axial trans disposition of the phenyl group at C13. The molecular structure with the numbering scheme is presented in Figure 1. The driving force for the Ph substituent at C13 to
and the phenyl substituent at S1 is 101.4°. The longer Pd−C bond trans to the carbene carbon (Pd−C26 = 2.167 Å) in comparison to the Pd−C bond trans to the sulfur atom (Pd− C28 = 2.123 Å) reflects the strong trans influence of the carbene. Moreover, for the bidentate complex (RS,SC)*-9, the M−S−C bond angles of C20−S1−Pd1 and C13−S1−Pd1 were found to be 105.2 and 96.8°, which are smaller than the observed angle for a tetrahedral geometry, and this accounts for the aforementioned steric factors. Selected bond lengths and bond angles are given in Table 1. Table 1. Selected Bond Lengths (Å) and Angles (deg) of (RS,SC)*-9 Pd1−C1 Pd1−S1 Pd1−C28 Pd1−C26 Pd1−C27 C1−N1 C1−N2 C13−S1 C13−H13 C13−N2 C13−C14 C20−S1
2.030(9) 2.366(2) 2.123(8) 2.167(9) 2.177(10) 1.368(11) 1.339(10) 1.836(10) 1.000 1.482(11) 1.510(12) 1.809(9)
N1−C1−Pd1 N2−C13−C14 C1−Pd1−C28 N2−C1−Pd1 N1−C1−N2 N2−C13−H13 C1−Pd1−S1 C20−S1−C13 C20−S1−Pd1 N2−C13−S1 C13−S1−Pd1 C1−Pd1−C26
137.6(6) 115.3(8) 105.1(3) 118.2(6) 104.0(7) 109.7 82.7(2) 101.4(4) 105.2(3) 106.2(6) 96.8(3) 172.0(3)
The four possible λ-ring conformations of the palladacycle 9 are shown in Figure 2. It needs to be noted that the isomers shown in Figure 2a are not expected to be formed in this current scenario, due to the equatorial−equatorial Ph−Ph repulsions in play.
Figure 1. Molecular structure of (RS,SC)*-9;. Thermal ellipsoids are drawn at the 50% probability level. Hydrogen atoms except H13 and the BF4− counteranion are omitted for clarity.
adopt the axial position is attributed to the steric repulsive interaction with the Ph substituent on the S1 atom within the PdCS coordination plane. Upon coordination, S1 becomes a stereogenic center that was formed with R absolute configuration, and this selectivity can be explained by the lower steric interactions due to the relative trans disposition of the neighboring Ph(α) group in the case of the isomer studied by X-ray crystallography. The monocationic complex exhibits the usual distortedsquare-planar geometry through coordination of palladium(II) ion, with a Ccarbene−Pd1 bond distance of 2.030 Å along with a C1−Pd1−S1 bite angle of 82.7°. The C20−S1−C13−C14 torsion angle between the phenyl substituent at the α-carbon
Figure 2. The possible isomers of complex (±)-9 in λ-ring conformation. 2390
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Organometallics
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Figure 3. Variable-temperature 1H NMR spectra for complex (±)-9 in CD2Cl2.
Scheme 2. Allylation Reaction of (±)-1-Phenylethanamine
catalytic activity of the racemic complexes 9−12 was evaluated in the allylation reaction of 1-phenylethanamine. The palladium-catalyzed allylation of 1-phenylethanamine with cinnamyl ethyl carbonate (Scheme 2) was investigated under various conditions. In the first series of experiments, catalytic amounts of complexes 9−12 (∼2 mol %) were reacted with a mixture of (±)-1-phenylethanamine (14g; 0.727 mmol) and cinnamyl ethyl carbonate (13a; 0.242 mmol) in dry THF (2 mL) at 50 °C for 15 h. Under these conditions, a complete conversion was observed with complex (±)-9, whereas complexes (±)-10, (±)-11, and (±)-12 exhibited only moderate reactivity (Table 2). Substrate Scope of Aliphatic Amines. We further screened a series of primary and secondary aliphatic amines for their reactivity toward amination of cinnamyl ethyl carbonate (13a; 0.242 mmol) using (±)-9 (∼2 mol %) in dry THF (2 mL) at 50 °C (Scheme 3), and the results are summarized in Table 3.
The NMR spectroscopic characterization of (±)-9 was assisted by a combination of 1H and 13C NMR spectroscopy experiments. Data from a variable-temperature 1H NMR spectroscopic investigation done for complex (±)-9, in the temperature range +23 to −57 °C (Figure 3), was collected using a dichloromethane-d2 solution. At 23 °C, the lH NMR spectrum shows the presence of two diastereomers of 9 in solution. As the temperature is lowered, each resonance signal tends to broaden as the rate of the interconversion process diminishes and finally undergoes a collapse at −17 °C. This temperature was considered as the coalescence point, where the signal is at its broadest and before any splitting was observed. The resonances of the allyl protons and aromatic protons provide evidence for the reduced rate of the dynamic process at lower temperatures. Hence, the low-temperature spectra displayed in Figure 3, indicating the chemical exchange of syn and anti protons of the allyl group, explicates the interconversion of a ⇄ a′ or b ⇄ b′ isomers (Figure 2), and further, the interconversion of the rotamers, i.e. a ⇄ b′ or b ⇄ a′, was not possible, as the latter requires higher temperatures. Hence, the palladacycle 9 obtained in this work was obtained in a regioselective manner with the λ(SC)-ring conformation. The aforementioned studies, while providing structural information for the synthesized complexes in both the solid and solution states, also yielded important insights for the future design of chiral variants. Catalytic Activity of Complexes 9−12. After obtaining insights into the coordination behavior of sulfur in palladium(II) π-allyl complexes from the aforementioned solid and solution state structural studies, we undertook an investigation to access their performances in catalytic allylic amination. The
Table 2. Reaction of Cinnamyl Ethyl Carbonate (13a) and (±)-1-Phenylethanamine (14g)a entry
[C]
additive
time (h)
temp (°C)
conv. (%)b (15g + 16g)
1 2 3 4
(±)-9 (±)-10 (±)-11 (±)-12
none none none none
15 15 15 15
50 50 50 50
96c 79c 75c 72c
Conditions: 0.242 mmol, 50 °C, 2 mL of THF was used. bIsolated yield. cDetermined by 1H NMR; contains both 15g (mono-allylated product) and 16g (bis-allylated product).
a
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Scheme 3. Reaction of Mono- and DiSubstituted Amines with (E)-Cinnamyl Carbonate
Table 3. Reaction of Amines 14a−j with (E)-Cinnamyl Carbonate (13a)a
Conditions: 0.242 mmol, 50 °C, 2 mL of THF was used. bIsolated yield. cIsolated yield of 15 (mono-allylated product) and 16 (bis-allylated product). a
NMR spectra, a doublet with a coupling range of 16 Hz in the range of 6.5 ppm for Ha (trans coupling) and a sextuplet (Hb) with a coupling of 6 Hz in the range of 6.2−6.3 ppm, followed by a doublet with a coupling of 6 Hz in the range of 3.14−3.16 ppm from the two Hc atoms, pointing out that trans linear products were obtained from trans substrates, with complete stereoretention. Substrate Scope of Allylic Carbonates. With the efficient reaction conditions for aliphatic amines toward allylic amination reaction established, we further investigated the scope and limitations of various α/γ mono- and disubstituted allylic carbonates. Under the previously optimized conditions, the reactions of morpholine and various α/γ mono- and disubstituted carbonates 13b−g were efficiently promoted by catalyst (±)-9 to provide the desired allylated products in high yields. Morpholine was used as the amine during the entire course of substrate studies on allylic carbonates in order to
The results collected in Table 3 show that both the primary and secondary aliphatic amines had a strong influence on the reaction rate and the product yields. The amination of cinnamyl ethyl carbonate (13a) worked well for the range of secondary amines tested, 14a−f (entries 1−6, Table 3), giving generally high yields of the corresponding allylated amine products. Conversely, primary amines 14g−j (entries 7−10, Table 3) gave moderate yields. This difference in reactivity could be related to the nucleophilicity of the corresponding amines. The reaction of naphthalen-1-ylmethanamine (14i) (entry 9, Table 3) and phenylmethanamine (14j) (entry 10, Table 3) under optimized conditions gave a higher percentage of bis-allylated product in comparison to 1-phenylethanamine (14g) (entry 7, Table 3) and its 1-(napththalen-1-yl)ethanamine counterpart (14h) (entry 8, Table 3), and these differences in reactivity could be attributed to the basicity of the corresponding amines. Additionally, all (E)-cinnamyl allyl amines gave similar 1H 2392
dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
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Table 4. Reaction of Morpholine (14d) with Allylic Carbonates 13b−ga
Conditions: 0.242 mmol, 50 °C, 2 mL of THF was used. bIsolated yield. cDetermined by 1H NMR spectroscopy, contains both 17f,g and 18f,g isomers, dE/Z mixture of 13c (E/Z = 4/1) was used. e∼4 mol % of (±)-9 was used. a
[Pd(η3-alkenyl)] intermediate complexes, which led to the formation of the mixture of isomers. The loss of stereochemistry of the α-substituted allylic carbonate 13f and highly branched α,α-disubstituted allylic carbonate 13g was due to rapid σ−η3−σ interconversion of the palladium(II) allyl intermediate complex in comparison to the slower rate of the amination reaction. With the highly substituted carbonate 13g (entry 6, Table 4), although the reaction proceeded more slowly and was complete in 96 h, quantitatively high chemical yields were achieved with mixtures of isomers. The reaction for the unsubstituted allylic carbonate is relatively fast, and high yields of the desired product were obtained. From the above results, it is significant that all the reactions proceeded with complete conversion, and hence we conclude that complex (±)-9 was indeed successful in inducing good regioselectivity for a range of substrates tested (aliphatic amines (primary and secondary alkyl substituted amines) and α-/γ-substituted allylic carbonates) toward allylic amination under mild and simple conditions, without any aid of activators such as triphenylphosphine, carboxylic acids, etc.
obtain a clear picture of the regioselective mechanism and thereby avoiding the bis-allylated products. The results for amination of allylic carbonates 13b−g with morpholine (14d) using (±)-9 are summarized in Table 4. At 50 °C, all allylic carbonates examined, 13a−g, underwent amination, giving the corresponding N-allylamines in overall isolated yields ranging from 68 to 98%. The reaction of allyl ethyl carbonate (13b) (entry 1, Table 4]) proceeded in a manner similar to that for the γ-phenyl-substituted carbonate 13a (entry 4, Table 3) with full conversion. The γ-methylsubstituted carbonate 13c (entry 2, Table 4) containing 20% of cis isomer underwent full conversion to yield the allylated products with a trans:cis ratio of 4:1, without any branched isomer; hence, we conclude that the trans substrate ionized initially to a more thermodynamically stable syn-[Pd(η3alkenyl)] intermediate complex, which then preferentially led to the formation of the trans linear product. (E)-3,7Dimethylocta-2,6-dienyl ethyl carbonate (13d) (entry 3, Table 4) gave exclusively the trans linear product with 98% yield. The allylation of morpholine with the α,γ-disubstituted carbonate 13e (entry 4, Table 4) also proceeded smoothly under the optimized conditions. Treatment of morpholine with the α-substituted allylic carbonate 13f and highly branched α,αdisubstituted allylic carbonate 13g (entries 5 and 6, Table 4) gave mixtures of the stereo- and regioisomeric amines 17f,g and 18f,g in 70% and 30% yields, respectively. The ratio of the product distribution shows that the products were derived via the π-allyl intermediate, where nucleophilic substitution is possible on both the C-1 and C-3 positions. The branched substrates ionized partially to syn-[Pd(η3-alkenyl)] and anti-
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CONCLUSION In summary, heterobidentate C,S ligands and their corresponding palladium(II) π-allyl complexes were successfully designed, developed, and completely characterized. Our studies showed that in the solid state the sulfur-functionalized NHC PdII allyl complex (±)-9 adopts the λ(SC)-ring conformation. The preferred catalyst (±)-9 has been structurally determined by single-crystal X-ray diffraction analysis of one of its diastereomers. This investigation along with a solution NMR 2393
dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
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synthesis of compound 2 was followed. Yield: 0.886 g (82%). 1H NMR (400 MHz, CDCl3): δ 10.52 (s, 1H, NCHN), 8.09 (s, 1H, NCHS), 7.89−7.92 (m, 2H, SArH), 7.60−7.64 (m, 2H, ArH), 7.56 (s, 1H, NCHCHN), 7.49 (s, 1H, NCHCHN) 7.42−7.44 (m, 3H, ArH), 7.29−7.33 (m, 3H, SArH), 1.47 (s, 9H, tBu). 13C NMR (100 MHz, CDCl3): δ 135.9, 134.0, 133.9, 130.3, 130.1, 129.6, 129.4, 129.3, 128.0, 119.4, 119.3, 67.1, 60.3, 29.8. HRMS: calcd for C20H23N2SBr [M − Br]+ 323.16, found 323.15. 1-(tert-Butyl)-3-((tert-butylthio)(phenyl)methyl)-1H-imidazol-3-ium Bromide (4). To a stirred solution of 3-(bromo(phenyl)methyl)-1-tert-butyl-1H-imidazol-3-ium bromide (1 g, 2.688 mmol) in dry dichloromethane (50 mL) at −10 °C was added sodium 2methylpropane-2-thiolate (0.3 g, 2.688 mmol). The procedure given for the synthesis of compound 2 was followed. Yield: 0.8 g (78%). 1H NMR (400 MHz, DMSO-d6): δ 9.86 (s, 1H, NCHN), 8.34 (s, 1H, NCHCHN), 8.17 (s, 1H, NCHCHN), 7.38−7.48 (m, 5H, ArH), 7.12 (s, 1H, NCHS), 1.61 (s, 9H, StBu), 1.29 (s, 9H, tBu). 13C NMR (100 MHz, DMSO-d6): δ 137.5, 133.9, 129.1, 129.0, 126.4, 121.7, 121.3, 64.0, 60.3, 46.5, 30.1, 28.9. HRMS: calcd for C18H27N2SBr [M − Br]+ 303.19, found 303.19. Silver Carbene 5. Silver(I) oxide (0.234 g, 1.006 mmol) was added to a solution of 3-mesityl-1-(phenyl(phenylthio)methyl)-1Himidazol-3-ium bromide (0.85 g, 1.831 mmol) in CH2Cl2 (25 mL), and the suspension was stirred for 4 h at room temperature in the dark. The mixture was filtered off through a small Celite plug and concentrated to afford the crude product. Yield: 0.9 g (89%). 1H NMR (400 MHz, CDCl3): δ 7.87−7.90 (m, 4H, ArH), 7.80−7.82 (m, 2H, NCHCHN), 7.67−7.71 (m, 2H, SArH), 7.58−7.60 (m, 2H, SArH), 7.53−7.56 (m, 4H, ArH), 7.48−7.50 (m, 4H, SArH), 7.44−7.46 (m, 2H, ArH), 7.33−7.34 (m, 1H, NCHCHN), 7.12 (s, 2H, SArH), 6.96 (s, 1H, NCHCHN), 6.85−6.91 (m, 6H, NCHS; ArH), 2.29 (s, 6H, ArMe), 1.90 (s, 3H, ArMe), 1.81 (s, 3H, ArMe), 1.67 (d, 3H, ArMe), 1.62 (d, 3H, ArMe). 13C NMR (100 MHz, CD3Cl):δ 139.6, 136.1, 134.5, 134.4, 133.9, 129.9, 129.6, 129.5, 129.4, 129.3, 129.3, 129.2, 126.6, 72.6, 21.0, 17.8, 17.6, 17.5. HRMS: calcd for C50H48AgN4S2 [M + H]+ 877.25, found 877.24. Silver Carbene 6. Silver(I) oxide (0.264 g, 1.137 mmol) was added to a solution of 1-tert-butyl-3-(phenyl(p-tolylthio)methyl)-1Himidazol-3-ium bromide (0.86 g, 2.067 mmol) in CH2Cl2 (25 mL), and the procedure given for the synthesis of compound 5 was followed. Yield: 0.92 g (86%). 1H NMR (400 MHz, CDCl3): δ 7.47− 7.48 (m, 2H, SArH), 7.38−7.43 (m, 3H, ArH), 7.30−7.31 (d, JH−H = 2.0 Hz, 1H, NCHCHN), 7.20−7.22 (m, 2H, ArH), 7.10−7.14 (m, 3H, NCHCHN; SArH), 6.91 (s, 1H, NCHS), 2.31 (s, 3H, SArMe), 1.56 (s, 9H, tBu).13C NMR (100 MHz, CDCl3): δ 139.79, 136.04, 134.62, 130.61, 129.42, 129.10, 127.17, 126.97, 119.76, 117.31, 74.10, 57.74, 31.64, 21.21. HRMS: calcd for C21H25N2SAgBr [M − Br]+ 443.07, found 443.07. Silver Carbene 7. Silver(I) oxide (0.280 g, 1.2 mmol) was added to a solution of 1-tert-butyl-3-(phenyl(phenylthio)methyl)-1H-imidazol-3-ium bromide (0.88 g, 2.189 mmol) in CH2Cl2 (25 mL), and the procedure given for the synthesis of compound 5 was followed. Yield: 0.958 g (86%). 1H NMR (400 MHz, CDCl3): δ 7.48−7.51 (m, 2H, ArH; NCHCHN), 7.41−7.43 (m, 3H, ArH), 7.32−7.35 (m, 2H, SArH; ArH), 7.14 (s, 1H, NCHCHN), 6.99 (s, 1H, NCHS), 1.56 (s, 9H, tBu).13C NMR (100 MHz, CD3Cl): δ 136.0, 134.5, 130.7, 129.9, 129.5, 129.4, 129.2, 127.0, 119.8, 117.3, 73.9, 57.8, 31.7, −0.03. HRMS: calcd for C20H23N2SAgBr [M − Br]+ 430.34, found 430.37. Silver Carbene 8. Silver(I) oxide (0.267 g, 1.15 mmol) was added to a solution of 1-(tert-butyl)-3-((tert-butylthio)(phenyl)methyl)-1Himidazol-3-ium bromide (0.8 g, 2.09 mmol) in CH2Cl2 (25 mL), and the procedure given for the synthesis of compound 5 was followed. Yield: 0.90 g (88%). 1H NMR (400 MHz, CDCl3): δ 7.56−7.57 (d, JH−H = 2 Hz, 1H, NCHCHN), 7.28−7.35 (m, 5H, ArH), 7.23 (d, JH−H = 2.0 Hz, 1H, NCHCHN), 6.91 (s, 1H, NCHS), 1.73 (s, 9H, StBu), 1.33 (s, 9H, tBu).13C NMR (100 MHz, CDCl3): δ 138.5, 129.0, 128.7, 126.5, 119.1, 118.4, 68.5, 58.1, 46.3, 31.8, 31.6, 30.9. HRMS: calcd for C18H27N2SAgBr [M − Br]+ 409.09, found 409.1.
analysis revealed factors that contribute to stereoselectivity factors in such synthetic protocols. An efficient and convenient catalytic system has been successfully developed for allylic amination reactions employing (±)-9. The catalyst was shown to promote allylic amination for a wide range of allylic carbonates as well as aliphatic amines, for the production of allylamines in a highly regioselective manner and typically in good yields in the absence of activators. Development of chiral variants and their application in asymmetric synthesis is currently being pursued in our laboratory.
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EXPERIMENTAL SECTION
General Methods. All reactions are carried under an inert atmosphere of argon using Schlenk line techniques in oven-dried glassware. Tetrahydrofuran was distilled from sodium benzophenone; dichloromethane and acetonitrile were distilled from calcium hydride immediately prior to use. All other solvents and reagents were used as received. [Pd(η3-C3H5)(COD)]+BF4− was prepared according to the literature procedures. 1H NMR and 13C NMR (400 and 100 MHz; 500 and 125 MHz) were recorded in CDCl3, CD2Cl2, CD3OD, and DMSO solutions using Bruker Avance 400 and 500 NMR spectrometers. Mass spectra were obtained on a Finnigan LCQ DECA XP MAX instrument with ESI mode. High-resolution mass spectra were obtained using a Water Q-Tof premier also with ESI mode. It is to be noted that, due to the hygroscopic nature of these compounds, elemental analysis data were not reproducible. 3-Mesityl-1-(phenyl(phenylthio)methyl)-1H-imidazol-3-ium Bromide (1). To a stirred solution of 3-(bromo(phenyl)methyl)-1mesityl-1H-imidazol-3-ium bromide (1 g, 2.304 mmol) in dry dichloromethane (50 mL) at −10 °C was added sodium benzenethiolate (0.304 g, 2.304 mmol). The reaction mixture was warmed to room temperature and stirred for another 4 h. On completion of the reaction, the reaction mixture was filtered and the filtrate was evaporated, followed by tituration with diethyl ether, to yield the desired crude product. The pure product was purified by column chromatography using silica gel and chloroform−methanol 100/3) as eluent. Yield: 0.856 g (80%). 1H NMR (400 MHz, CDCl3): δ 10.87 (s, 1H, NCHN), 8.76 (s, 1H, NCHS), 7.97−7.98 (d, JH−H = 6.8 Hz, 2H, ArH), 7.88 (s, 1H, NCHCHN), 7.77−7.90 (d, JH−H = 7.6 Hz, 2H, SArH), 7.44−7.49 (m, 3H, ArH), 7.32−7.36 (t, JH−H = 7.6 Hz, 2H, SArH), 7.27−7.29 (m, 1H, SArH), 6.95 (s, 1H, NCH CHN), 6.91 (s, 1H, ArH), 6.88 (s, 1H, ArH), 2.29 (s, 3H, ArMe), 1.93 (s, 3H, ArMe), 1.51 (s, 3H, ArMe).13C-NMR (100 MHz, CDCl3): δ 141.4, 137.8, 134.4, 134.1, 133.9, 133.2, 130.3, 130.3, 130.0, 129.8, 129.7, 129.5, 129.1, 127.8, 123.3, 120.2, 66.7, 21.1, 17.6, 17.0. HRMS: calcd for C25H25N2SBr [M − Br]+ 385.17, found 385.91. 1-(tert-Butyl)-3-(phenyl(p-tolylthio)methyl)-1H-imidazol-3ium Bromide (2). To a stirred solution of 3-(bromo(phenyl)methyl)1-tert-butyl-1H-imidazol-3-ium bromide (1 g, 2.688 mmol) in dry dichloromethane (50 mL) at −10 °C was added sodium 4methylbenzenethiolate (0.393 g, 2.689 mmol). The reaction mixture was warmed to room temperature and stirred for another 4 h. On completion of the reaction, the reaction mixture was filtered and the filtrate was evaporated, followed by tituration with diethyl ether to yield the desired crude product. The residue was chromatographed on silica gel with of methanol−chloroform (100/3) as eluent to yield the desired product 2 as white hygroscopic solids. Yield; 0.864 g (80%). 1 H NMR (400 MHz, CD2Cl2): δ 10.60 (s, 1H, NCHN), 8.06 (s, 1H, NCHS), 7.86−7.88 (m, 2H, SArH), 7.52 (s, 1H, NCHCHN), 7.44−7.49 (m, 5H, ArH), 7.15 (s, 1H, SArH), 7.12−7.13 (m, 2H, SArH; NCHCHN), 2.30 (s, 3H, SArMe), 1.44 (s, 9H, tBu). 13C NMR (100 MHz, CD2Cl2): δ 140.0, 136.2, 134.4, 134.2, 130.3, 130.2, 129.3, 127.9, 126.7, 119.3, 119.1, 67.2, 29.6, 20.9, −0.4. HRMS: calcd for C21H25N2SBr [M − Br]+ 337.17, found 337.17. 1-(tert-Butyl)-3-(phenyl(phenylthio)methyl)-1H-imidazol-3ium Bromide (3). To a stirred solution of 3-(bromo(phenyl)methyl)1-tert-butyl-1H-imidazol-3-ium bromide (1 g, 2.689 mmol) in dry dichloromethane (50 mL) at −10 °C was added sodium benzenethiolate (0.354 g, 2.689 mmol). The procedure given for the 2394
dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
Organometallics
Article
Palladium Complex (±)-9 (Mixture of Two Diastereomers in 1:1 Ratio).
= 2.1 Hz, 1H), 7.45−7.46 (d, JH−H = 2.0 Hz, 0.5H), 7.36−7.43 (m, 6H), 7.32−7.36 (m, 2H), 7.22−7.27 (m, 2H), 7.10−7.12 (m, 2H), 7.05−7.07 (s, 0.5H), 6.88−6.91 (s, 0.5H), 5.75−5.87 (septet, JH−H = 6.8 Hz, 1H, Hc), 5.61−5.73 (septet, JH−H = 6.7 Hz, 0.5H, H′c), 4.77− 4.82 (d, JH−H = 7.1 Hz, 0.5H, H′e), 4.61−4.66 (d, JH−H = 7.3 Hz, 1H, He), 4.46−4.53 (m, 1.5H, Ha and H′a), 3.69−3.76 (d, JH−H = 13.5 Hz, 1H, Hd), 3.46−3.54 (m, 1H, H′d), 3.28 (m, 0.3H, H′b), 3.16−3.22 (d, JH−H = 13.5 Hz, 1H, Hb), 1.85 (s, 4.5H, tBu), 1.83 (s, 9H, tBu), 1.70 (s, 4.5H, tBu), 1.51 (s, 4H, StBu), 1.41 (s, 9H, StBu), 1.37 (s, 4.5H, StBu). 13C-NMR (100 MHz, CD2Cl2): δ 177.8, 177.7, 137.6, 136.3, 136.0, 133.8, 129.6, 129.5, 129.3, 129.2, 129.2, 126.4, 126.3, 126.2, 121.1, 121.0, 120.8, 119.9, 119.6, 119.0, 118.9, 70.8, 67.3, 67.1, 67.1, 65.5, 59.1, 59.0, 55.0, 53.8, 47.1, 30.9, 30.9, 30.4, 30.3, 30.2, 29.5. HRMS: calcd for C21H33N2PdSBF4 [M − BF4]+ 450.13, found 450.13. General Procedure for Allylic Amination. The appropriate palladium(II) π-allyl complex (3.02 mg, ∼2 mol %, 0.02 equiv), was added to a dry screw-cap reaction tube containing cinnamyl ethyl carbonate (50.0 mg, 0.242 mmol, 1 equiv), followed by primary or secondary amines (0.727 mmol, 3 equiv) in dry THF (2 mL). The whole reaction tube was heated to 50 °C until the reaction reached completion (determined through thin-layer chromatography). After the disappearance of starting material, the reaction mixture was cooled to room temperature and the THF was removed under reduced pressure. The residue was then diluted with diethyl ether and filtered through a pad of silica gel. The ether layer was extracted with water and dried over MgSO4. The layer was concentrated and purified through silica gel column chromatography to give the desired amination product, determined through 1H NMR, 13C NMR and high-resolution mass spectroscopy. Single-Crystal X-ray Crystallographic Studies. Crystal data for (Rs,S)-9 were collected on a Bruker X8 CCD diffractometer with Mo Kα radiation (graphite monochromator). SADABS absorption corrections were applied. All non-hydrogen atoms were refined anisotropically, while hydrogen atoms were introduced at calculated positions and refined riding on their carrier atoms. CCDC 853452 contains supplementary crystallographic data for (Rs,S)-9. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
To a stirred solution of the complex silver carbene complex (5 ; 0.9 g, 1.58 mmol) in dichloromethane (20 mL) was added [Pd(η3C3H5)(COD)]+BF4−, (0.560 g, 1.58 mmol) under an argon atmosphere. The mixture was stirred in the dark for 4 h at room temperature, filtered through Celite, and concentrated, and the residue was titurated with hexane to afford complex 9, as a grayish white powder. Yield: 0.87 g (90%). 1H NMR (500 MHz, CD3OD): δ 7.65− 7.72 (d, JH−H = 8.0 Hz, 2H), 7.52−7.59 (m, 8H), 7.37−7.49 (m, 10H), 7.30−7.35 (m, 2H), 7.26−7.22 (m, 6H), 7.16−7.19 (s, 2H), 5.52− 5.39 m, 2H, Hc and H′c), 4.36−4.46 (d, JH−H = 7.3 Hz, 2H, He and H′e), 3.24−3.29 (m, 2H, H′a and H′d), 3.09−3.14 (d, JH−H = 13.5 Hz, 1H, Hd), 3.02−3.06 (d, JH−H = 7.3 Hz, 1H, Ha), 2.84−2.90 (d, JH−H = 12.6 Hz, 1H, H′b), 2.63−2.71 (dd, JH−H = 13.6 Hz, 1H, Hb), 2.43 (s, 6H, ArMe), 2.18 (s, 3H, ArMe), 2.05−2.14 (d, JH−H = 15 Hz, 6H, ArMe), 1.99 (s, 3H, ArMe). 13C NMR (100 MHz, CDCl3): δ 179.9, 140.2, 136.6, 135.6, 135.3, 134.9, 134.5, 133.2, 133.1, 131.3, 130.3, 130.2, 130.1, 130.0, 129.5, 129.4, 129.3, 129.1, 129.0, 128.6, 127.3, 123.9, 123.8, 122.2, 122.1, 119.8, 119.1, 75.0, 69.4, 69.2, 60.6, 60.1, 21.2, 17.7, 17.6, 17.6. HRMS: calcd for C28H31N2PdSBF4 [M − BF4]+ 533.13, found 533.12. Palladium Complex (±)-10 (Mixture of Two Diastereomers in 1:1 Ratio). The complex was prepared in a manner analogous to that described for (±)-9, using silver carbene complex (6; 0.92 g, 1.76 mmol) in dichloromethane (20 mL) and [Pd(η 3 -C 3 H 5 )(COD)]+SbF6− (0.602 g, 1.76 mmol) under an argon atmosphere. Yield: 0.91 g (90%), as a white powder. 1H NMR (400 MHz, CD2Cl2): δ 7.33−7.43 (m, 12H), 7.19−7.28 (m, 6H), 7.12−7.16 (m, 3H), 7.00 (s, 1H, NCHS), 6.41−6.60 (m, 2H), 5.59−5.77 (m, 2H, Hc and H′c), 4.67−4.72 (dd, JH−H = 5.6 Hz, 2H, He and H′e), 4.31−4.41 (d, JH−H = 6.2 Hz, 2H, Ha and H′a), 3.45−3.70 (dd, JH−H = 12.8 Hz, 2H, Hd and H′d), 3.11−3.25 (dd, JH−H = 13.0 Hz, 2H, Hb and H′b), 2.37 (s, 3H, SArMe), 2.35 (s, 3H, SArMe), 1.83−1.84 (d, JH−H = 3.6 Hz, 18H, tBu). 13C NMR (100 MHz, CD2Cl2): δ 177.8, 177.5, 142.9, 142.7, 134.5, 133.6, 133.3, 130.8, 130.8, 130.4, 130.3, 129.4, 129.3, 127.3, 126.9, 121.1, 120.8, 119.5, 119.5, 119.3, 70.7, 70.5, 68.3, 68.1, 59.3, 59.2, 31.0, 30.9, 21.1, 21.0. HRMS: calcd for C24H31N2PdSBF4 [M − BF4]+ 484.12, found 484.12. Palladium Complex (±)-11 (Mixture of Two Diastereomers in 1:1 Ratio). The complex was prepared in a manner analogous to that described for (±)-9, using silver carbene complex (7; 0.958 g, 1.889 mmol) in dichloromethane (20 mL) and [Pd(η3-C3H5)(COD)]+SbF6− (0.646 g, 1.889 mmol) under an argon atmosphere. Yield: 0.94 g (90%), as a white powder. 1H NMR (400 MHz, CD2Cl2): δ 7.33−7.70 (m, 18H), 7.22−7.32 (b, 2H), 7.10−7.21 (m, 3H), 7.01−7.06 (s, 1H, NCHS), 6.71−6.78 (m, 2H), 5.58−5.82 (m, 2H, Hc and H′c), 4.62−4.78 (dd, JH−H = 6.4 Hz, 2H, He and H′e), 4.35−4.45 (d, JH−H = 7.3 Hz, 2H, Ha and H′a), 3.50−3.72 (dd, JH−H = 13.0 Hz, 2H, Hd and H′d), 3.14−3.27 (d, JH−H = 13.4 Hz, 2H, Hb and H′b), 1.73−1.93 (d, JH−H = 4.1 Hz, 18H, tBu). 13C NMR (100 MHz, CD2Cl2): δ 177.7, 177.5, 134.4, 133.6, 133.4, 131.8, 131.7, 130.4, 130.4, 130.2, 130.1, 129.4, 129.3, 127.3, 126.9, 121.1, 120.8, 119.6, 119.5, 119.3, 70.9, 70.6, 68.5, 68.2, 59.3, 59.3, 31.0, 30.9, 29.0. HRMS: calcd for C23H29N2PdSBF4 [M − BF4]+ 470.12, found 470.13. Palladium Complex (±)-12 (Mixture of Three Diastereomers in 2:1:1 Ratio). The complex was prepared in a manner analogous to that described for (±)-9, using silver carbene complex (8; 0.9 g, 1.844 mmol) in dichloromethane (20 mL) and [Pd(η 3 -C 3 H 5 )(COD)]+SbF6− (0.957 g, 1.844 mmol) under an argon atmosphere. Yield : 0.990 g (92%), as a white powder. 1H NMR (500 MHz, CD3OD): δ 8.10−8.13 (d, JH−H = 2.2 Hz, 0.5H), 7.97−7.99 (d, JH−H = 2.2 Hz, 0.5H), 7.65−7.67 (d, JH−H = 2.1 Hz, 1.5H), 7.46−7.48 (d, JH−H
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ASSOCIATED CONTENT
S Supporting Information *
Figures giving spectral characterization data of allylated amines and 1H and 13C NMR spectra of palladium(II) π-allyl complexes (±)-9−(±)-12 and a CIF file giving crystallographic data for (Rs,S)-9. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*Tel: (65) 6316 8905. Fax: (+65) 6316 6984. E-mail:
[email protected] (P.-H.L.);
[email protected] (S.A.P.). Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We thank Nanyang Technological University for support of this research work and also funding research scholarship to D. Krishnan.
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REFERENCES
(1) (a) Wanzlick, H. W. Angew. Chem., Int. Ed. 1962, 74 (4), 129. (b) Wanzlick, H. W.; Kleiner, H. J. Angew. Chem., Int. Ed. 1961, 73 (14), 493. (c) Wanzlick, H. W.; Schikora, E. Angew. Chem., Int. Ed. 1960, 72 (14), 494−494. (2) Ö fele, K. J. Organomet. Chem. 1968, 12 (3), 42. (3) (a) Wang, F. J.; Liu, L. J.; Wang, W. F.; Li, S. K.; Shi, M. Coord. Chem. Rev. 2012, 256 (9−10), 804−853. (b) Benhamou, L.; Chardon, 2395
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Article
251 (5−6), 610−641. (e) Gade, L. H.; Bellemin-Laponnaz, S. Coord. Chem. Rev. 2007, 251 (5−6), 718−725. (f) Jung, I. G.; Seo, J.; Lee, S. I.; Choi, S. Y.; Chung, Y. K. Organometallics 2006, 25 (18), 4240− 4242. (g) Perry, M. C.; Burgess, K. Tetrahedron-Asymmetry 2003, 14 (8), 951−961. (8) (a) Krishnan, D.; Pullarkat, S. A.; Wu, M.; Li, Y.; Leung, P.-H. Chem. Eur. J. 2013, DOI: 10.1002/chem.201204320. (b) Canovese, L.; Visentin, F.; Levi, C.; Santo, C.; Bertolasi, V. Inorg. Chim. Acta 2012, 390, 105−118. (c) Bierenstiel, M.; Cross, E. D. Coord. Chem. Rev. 2011, 255 (5−6), 574−590. (d) Fliedel, C.; Sabbatini, A.; Braunstein, P. Dalton Trans. 2010, 39 (37), 8820−8828. (e) Fliedel, C.; Braunstein, P. Organometallics 2010, 29 (21), 5614−5626. (f) Huynh, H. V.; Chew, Y. X. Inorg. Chim. Acta 2010, 363 (9), 1979−1983. (g) Huynh, H. V.; Yeo, C. H.; Chew, Y. X. Organometallics 2010, 29 (6), 1479−1486. (h) Huynh, H. V.; Yuan, D.; Han, Y. Dalton Trans. 2009, 35, 7262−7268. (i) Fliedel, C.; Schnee, G.; Braunstein, P. Dalton Trans. 2009, 14, 2474−2476. (j) Gandolfi, C.; Heckenroth, M.; Neels, A.; Laurenczy, G.; Albrecht, M. Organometallics 2009, 28 (17), 5112−5121. (k) Iglesias-Siguenza, J.; Ros, A.; Diez, E.; Magriz, A.; Vazquez, A.; Alvarez, E.; Fernandez, R.; Lassaletta, J. M. Dalton Trans. 2009, 40, 8485−8488. (l) McGuinness, D. S.; Suttil, J. A.; Gardiner, M. G.; Davies, N. W. Organometallics 2008, 27 (16), 4238−4247. (m) Ros, A.; Alcarazo, M.; IglesiasSiguenza, J.; Diez, E.; Alvarez, E.; Fernandez, R.; Lassaletta, J. M. Organometallics 2008, 27 (18), 4555−4564. (n) Roseblade, S. J.; Ros, A.; Monge, D.; Alcarazo, M.; Alvarez, E.; Lassaletta, J. M.; Fernandez, R. Organometallics 2007, 26 (10), 2570−2578. (o) Kuriyama, M.; Shimazawa, R.; Shirai, R. Tetrahedron 2007, 63 (38), 9393−9400. (p) Pugh, D.; Danopoulos, A. A. Coord. Chem. Rev. 2007, 251 (5−6), 610−641. (q) Wolf, J.; Labande, A.; Daran, J. C.; Poli, R. Eur. J. Inorg. Chem. 2007, 32, 5069−5079. (r) Huynh, H. V.; Yeo, C. H.; Tan, G. K. Chem. Commun. 2006, 36, 3833−3835. (s) Ros, A.; Monge, D.; Alcarazo, M.; Alvarez, E.; Lassaletta, J. M.; Fernandez, R. Organometallics 2006, 25 (26), 6039−6046. (t) Cabeza, J. A.; del Rio, I.; Sanchez-Vega, M. G.; Suarez, M. Organometallics 2006, 25 (7), 1831− 1834. (u) Cabeza, J. A.; da Silva, I.; del Rio, I.; Sanchez-Vega, M. G. Dalton Trans. 2006, 33, 3966−3971. (v) Cantat, T.; Mezailles, N.; Ricard, L.; Jean, Y.; Le Floch, P. Angew. Chem., Int. Ed. 2004, 43 (46), 6382−6385. (w) Seo, H.; Park, H.; Kim, B. Y.; Lee, J. H.; Son, S. U.; Chung, Y. K. Organometallics 2003, 22 (4), 618−620. (x) Sellmann, D.; Allmann, C.; Heinemann, F.; Knoch, F.; Sutter, J. J. Organomet. Chem. 1997, 541 (1−2), 291−305. (y) Matsumura, N.; Kawano, J.; Fukunishi, N.; Inoue, H.; Yasui, M.; Iwasaki, F. J. Am. Chem. Soc. 1995, 117 (12), 3623−3624. (z) Sellmann, D.; Prechtel, W.; Knoch, F.; Moll, M. Organometallics 1992, 11 (7), 2346−2348. (9) (a) Begouin, J. M.; Klein, J. E. M. N.; Weickmann, D.; Plietker, B. Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis; Springer: Berlin, 2012; Topics in Organometallic Chemistry 38, pp 269−320. (b) Sundararaju, B.; Achard, M.; Bruneau, C. Chem. Soc. Rev. 2012, 41 (12), 4467−4483. (c) Lafrance, M.; Roggen, M.; Carreira, E. M. Angew. Chem., Int. Ed. 2012, 51 (14), 3470−3473. (d) Nemoto, T.; Hamada, Y. J. Synth. Org. Chem. Jpn. 2011, 69 (7), 763−774. (e) Ohshima, T.; Miyamoto, Y.; Ipposhi, J.; Nakahara, Y.; Utsunomiya, M.; Mashima, K. J. Am. Chem. Soc. 2009, 131 (40), 14317−14328. (f) Onitsuka, K. J. Synth. Org. Chem. Jpn. 2009, 67 (6), 584−594. (g) Evans, P. A.; Clizbe, E. A. J. Am. Chem. Soc. 2009, 131 (25), 8722. (h) Madrahimov, S. T.; Markovic, D.; Hartwig, J. F. J. Am. Chem. Soc. 2009, 131 (21), 7228. (i) Nemoto, T. Chem. Pharm. Bull. 2008, 56 (9), 1213−1228. (j) Diez-Gonzalez, S.; Nolan, S. P. Coord. Chem. Rev. 2007, 251 (5−6), 874−883. (k) Douthwaite, R. E. Coord. Chem. Rev. 2007, 251 (5−6), 702− 717. (l) Utsunomiya, M.; Miyamoto, Y.; Ipposhi, J.; Ohshima, T.; Mashima, K. Org. Lett. 2007, 9 (17), 3371−3374. (m) Leitner, A.; Shu, C. T.; Hartwig, J. F. Org. Lett. 2005, 7 (6), 1093−1096. (n) Caporali, M.; Muller, C.; Staal, B. B.; Tooke, D. M.; Spek, A. L.; van Leeuwen, P. W. Chem. Commun. 2005, 27, 3478−3480. (o) Belda, O.; Moberg, C. Acc. Chem. Res. 2004, 37 (3), 159−167. (p) Evans, P. A.; Lawler, M. J. J. Am. Chem. Soc. 2004, 126 (28), 8642−8643. (q) Shu, C. T.; Hartwig, J. F. Angew. Chem., Int. Ed. 2004, 43 (36), 4794−4797.
E.; Lavigne, G.; Bellemin-Laponnaz, S.; César, V. Chem. Rev. 2011, 111 (4), 2705−2733. (c) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int. Ed. 2008, 47 (17), 3122−3172. (d) Arnold, P. L.; Pearson, S. Coord. Chem. Rev. 2007, 251 (5−6), 596−609. (e) Sommer, W. J.; Weck, M. Coord. Chem. Rev. 2007, 251 (5−6), 860−873. (f) Mata, J. A.; Poyatos, M.; Peris, E. Coord. Chem. Rev. 2007, 251 (5−6), 841−859. (g) Douthwaite, R. E. Coord. Chem. Rev. 2007, 251 (5−6), 702−717. (h) Lin, I. J. B.; Vasam, C. S. Coord. Chem. Rev. 2007, 251 (5−6), 642−670. (i) Phan, N. T. S.; Van Der Sluys, M.; Jones, C. W. Adv. Synth. Catal. 2006, 348 (6), 609−679. (j) Garrison, J. C.; Youngs, W. J. Chem. Rev. 2005, 105 (11), 3978−4008. (k) Peris, E.; Crabtree, R. H. Coord. Chem. Rev. 2004, 248 (21−24), 2239−2246. (l) Bedford, R. B.; Cazin, C. S. J.; Holder, D. Coord. Chem. Rev. 2004, 248 (21−24), 2283−2321. (m) César, V.; Bellemin-Laponnaz, S.; Gade, L. H. Chem. Soc. Rev. 2004, 33 (9), 619−636. (n) Viciu, M. S.; Navarro, O.; Germaneau, R. F.; Kelly, R. A.; Sommer, W.; Marion, N.; Stevens, E. D.; Cavallo, L.; Nolan, S. P. Organometallics 2004, 23 (7), 1629−1635. (o) Hillier, A. C.; Grasa, G. A.; Viciu, M. S.; Lee, H. M.; Yang, C. L.; Nolan, S. P. J. Organomet. Chem. 2002, 653 (1−2), 69−82. (p) Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41 (8), 1290−1309. (q) Viciu, M. S.; Germaneau, R. F.; Navarro-Fernandez, O.; Stevens, E. D.; Nolan, S. P. Organometallics 2002, 21 (25), 5470−5472. (r) Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100 (8), 3009−3066. (s) Bourissou, D.; Guerret, O.; Gabbai, F. P.; Bertrand, G. Chem. Rev. 2000, 100 (1), 39−91. (4) (a) Danopoulos, A. A.; Tsoureas, N.; Macgregor, S. A.; Smith, C. Organometallics 2007, 26 (2), 253−263. (b) Lee, C. C.; Ke, W. C.; Chan, K. T.; Lai, C. L.; Hu, C. H.; Lee, H. M. Chem. Eur. J. 2007, 13 (2), 582−591. (c) Wolf, J.; Labande, A.; Daran, J. C.; Poli, R. J. Organomet. Chem. 2006, 691 (3), 433−443. (d) Hahn, F. E.; Jahnke, M. C.; Pape, T. Organometallics 2006, 25 (25), 5927−5936. (e) Hodgson, R.; Douthwaite, R. E. J. Organomet. Chem. 2005, 690 (24−25), 5822−5831. (f) Zeng, J. Y.; Hsieh, M. H.; Lee, H. M. J. Organomet. Chem. 2005, 690 (24−25), 5662−5671. (g) Field, L. D.; Messerle, B. A.; Vuong, K. Q.; Turner, P. Organometallics 2005, 24 (17), 4241−4250. (h) Jones, N. D.; Cavell, R. G. J. Organomet. Chem. 2005, 690 (24−25), 5485−5496. (i) Chiu, P. L.; Lee, H. M. Organometallics 2005, 24 (7), 1692−1702. (j) Lee, H. M.; Zeng, J. Y.; Hu, C. H.; Lee, M. T. Inorg. Chem. 2004, 43 (21), 6822−6829. (k) Tsoureas, N.; Danopoulos, A. A.; Tulloch, A. A. D.; Light, M. E. Organometallics 2003, 22 (23), 4750−4758. (l) Weskamp, T.; Bohm, V. P. W.; Herrmann, W. A. J. Organomet. Chem. 2000, 600 (1−2), 12− 22. (5) (a) Chiang, M. Y.; Li, Y. X.; Krishnan, D.; Sumod, P.; Ng, K. H.; Leung, P. H. Eur. J. Inorg. Chem. 2010, 9, 1413−1418. (b) Jahnke, M. C.; Pape, T.; Hahn, F. E. Eur. J. Inorg. Chem. 2009, 13, 1960−1969. (c) Jimenez, M. V.; Perez-Torrente, J. J.; Bartolome, M. I.; Gierz, V.; Lahoz, F. J.; Oro, L. A. Organometallics 2008, 27 (2), 224−234. (d) Stylianides, N.; Danopoulos, A. A.; Tsoureas, N. J. Organomet. Chem. 2005, 690 (24−25), 5948−5958. (e) Gade, L. H.; César, V.; Bellemin-Laponnaz, S. Angew. Chem., Int. Ed. 2004, 43 (8), 1014− 1017. (f) Cesar, V.; Bellemin-Laponnaz, S.; Gade, L. H. Organometallics 2002, 21 (24), 5204−5208. (g) McGuinness, D. S.; Cavell, K. J. Organometallics 2000, 19 (5), 741−748. (6) (a) Jones, N. A.; Liddle, S. T.; Wilson, C.; Arnold, P. L. Organometallics 2007, 26 (3), 755−757. (b) Arnold, P. L.; Rodden, M.; Wilson, C. Chem. Commun. 2005, 13, 1743−1745. (c) Clavier, H.; Coutable, L.; Toupet, L.; Guillemin, J. C.; Mauduit, M. J. Organomet. Chem. 2005, 690 (23), 5237−5254. (d) Arnold, P. L.; Rodden, M.; Davis, K. M.; Scarisbrick, A. C.; Blake, A. J.; Wilson, C. Chem. Commun. 2004, 14, 1612−1613. (e) Waltman, A. W.; Grubbs, R. H. Organometallics 2004, 23 (13), 3105−3107. (f) Arnold, P. L.; Scarisbrick, A. C.; Blake, A. J.; Wilson, C. Chem. Commun. 2001, 22, 2340−2341. (7) (a) Budagumpi, S.; Haque, R. A.; Salman, A. W. Coord. Chem. Rev. 2012, 256 (17−18), 1787−1830. (b) Normand, A. T.; Cavell, K. J. Eur. J. Inorg. Chem. 2008, 18, 2781−2800. (c) Kantchev, E. A. B.; O’Brien, C. J.; Organ, M. G. Angew. Chem., Int. Ed. 2007, 46 (16), 2768−2813. (d) Pugh, D.; Danopoulos, A. A. Coord. Chem. Rev. 2007, 2396
dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
Organometallics
Article
(r) Shu, C. T.; Leitner, A.; Hartwig, J. F. Angew. Chem., Int. Ed. 2004, 43 (36), 4797−4800. (s) Bartels, B.; Garcia-Yebra, C.; Helmchen, G. Eur. J. Org. Chem. 2003, 6, 1097−1103. (t) Evans, P. A.; Leahy, D. K. J. Am. Chem. Soc. 2003, 125 (30), 8974−8975. (u) Kiener, C. A.; Shu, C. T.; Incarvito, C.; Hartwig, J. F. J. Am. Chem. Soc. 2003, 125 (47), 14272−14273. (v) Bartels, B.; Garcia-Yebra, C.; Rominger, F.; Helmchen, G. Eur. J. Inorg. Chem. 2002, 10, 2569−2586. (w) Trost, B. M.; Dogra, K. J. Am. Chem. Soc. 2002, 124 (25), 7256−7257. (x) Evans, P. A.; Robinson, J. E.; Moffett, K. K. Org. Lett. 2001, 3 (21), 3269−3271. (y) Kamer, P. C. J.; van Leeuwen, P. W. N.; Reek, J. N. H. Acc. Chem. Res. 2001, 34 (11), 895−904. (z) Takeuchi, R.; Ue, N.; Tanabe, K.; Yamashita, K.; Shiga, N. J. Am. Chem. Soc. 2001, 123 (39), 9525−9534. (aa) Takeuchi, R.; Tanabe, K. Angew. Chem., Int. Ed. 2000, 39 (11), 1975. (ab) Bartels, B.; Helmchen, G. Chem. Commun. 1999, No. 8, 741−742. (ac) Fuji, K.; Kinoshita, N.; Tanaka, K.; Kawabata, T. Chem. Commun. 1999, 22, 2289−2290. (ad) Glorius, F.; Pfaltz, A. Org. Lett. 1999, 1 (1), 141−144. (ae) Evans, P. A.; Nelson, J. D. J. Am. Chem. Soc. 1998, 120 (22), 5581−5582. (af) Takeuchi, R.; Kashio, M. J. Am. Chem. Soc. 1998, 120 (34), 8647−8655. (10) (a) Liu, L.; Ma, H. L.; Fu, B. Molecules 2012, 17 (2), 1992− 1999. (b) Poli, G.; Prestat, G.; Liron, F.; Kammerer-Pentier, C. Selectivity in Palladium-Catalyzed Allylic Substitution. In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis; Kazmaier, U., Ed.; Springer: Berlin, 2012; Topics in Organometallic Chemistry 38, pp 1−63. (c) Wang, Y.; Vaismaa, M. J. P.; Rissanen, K.; Franzen, R. Eur. J. Org. Chem. 2012, 8, 1569−1576. (d) Mahadik, G. S.; Knott, S. A.; Szczepura, L. F.; Peters, S. J.; Standard, J. M.; Hitchcock, S. R. J. Org. Chem. 2009, 74 (21), 8164−8173. (e) Chen, H. F.; Sweet, J. A.; Lam, K. C.; Rheingold, A. L.; McGrath, D. V. Tetrahedron-Asymmetry 2009, 20 (14), 1672−1682. (f) Flahaut, A.; Roland, S.; Mangeney, P. Tetrahedron-Asymmetry 2007, 18 (2), 229− 236. (g) Cortes, J. G. L.; Ramon, O.; Vincendeau, S.; Serra, D.; Lamy, F.; Daran, J. C.; Manoury, E.; Gouygou, M. Eur. J. Inorg. Chem. 2006, 24, 5148−5157. (h) Anderson, J. C.; Osborne, J. Tetrahedron: Asymmetry 2005, 16 (5), 931−934. (i) Pamies, O.; Dieguez, M.; Claver, C. J. Am. Chem. Soc. 2005, 127 (11), 3646−3647. (j) Acemoglu, L.; Williams, J. M. J., Palladium-Catalyzed Asymmetric Allylation and Related Reactions. In Handbook of Organopalladium Chemistry for Organic Synthesis; Wiley: Hoboken, NJ, 2003; pp 1945−1979. (k) Acemoglu, L.; Williams, J. M. J. The Tsuji−Trost Reaction and Related Carbon−Carbon Bond Formation Reactions: Synthetic Scope of the Tsuji−Trost Reaction with Allylic Halides, Carboxylates, Ethers, and Related Oxygen Nucleophiles as Starting Compounds. In Handbook of Organopalladium Chemistry for Organic Synthesis; Wiley: Hoboken, NJ, 2003; pp 1689−1705. (l) Trost, B. M.; Toste, F. D. J. Am. Chem. Soc. 1999, 121 (19), 4545−4554. (11) (a) Cao, Z. P.; Liu, Y. L.; Liu, Z. Q.; Feng, X. Q.; Zhuang, M. Y.; Du, H. F. Org. Lett. 2011, 13 (9), 2164−2167. (b) Mata, Y.; Pamies, O.; Dieguez, M. Adv. Synth. Catal. 2009, 351 (18), 3217−3234. (c) Svensen, N.; Fristrup, P.; Tanner, D.; Norrby, P. O. Adv. Synth. Catal. 2007, 349 (17−18), 2631−2640. (d) Flahaut, A.; Roland, S.; Mangeney, P. J. Organomet. Chem. 2007, 692 (26), 5754−5762. (e) Piechaczyk, O.; Thoumazet, C.; Jean, Y.; le Floch, P. J. Am. Chem. Soc. 2006, 128 (44), 14306−14317. (f) Yang, S. C.; Hsu, Y. C.; Gan, K. H. Tetrahedron 2006, 62 (17), 3949−3958. (g) Kinoshita, H.; Shinokubo, H.; Oshima, K. Org. Lett. 2004, 6 (22), 4085−4088. (h) Ozawa, F.; Ishiyama, T.; Yamamoto, S.; Kawagishi, S.; Murakami, H. Organometallics 2004, 23 (8), 1698−1707. (i) Ozawa, F.; Okamoto, H.; Kawagishi, S.; Yamamoto, S.; Minami, T.; Yoshifuji, M. J. Am. Chem. Soc. 2002, 124 (37), 10968−10969. (12) Roland, S.; Cotet, W.; Mangeney, P. Eur. J. Inorg. Chem. 2009, 13, 1796−1805. (13) Wang, H. M. J.; Lin, I. J. B. Organometallics 1998, 17 (5), 972− 975.
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dx.doi.org/10.1021/om400110t | Organometallics 2013, 32, 2389−2397
