Ir-Catalyzed Selective Hydroboration of 2-Substituted 1,3-Dienes: A

Subscriber access provided by University of South Dakota

Article

Ir-Catalyzed Selective Hydroboration of 2-Substituted 1,3Dienes: A General Method to Access Homoallylic Boronates Daniele Fiorito, and Clément Mazet ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.8b02334 • Publication Date (Web): 30 Aug 2018 Downloaded from http://pubs.acs.org on August 30, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 7 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

Ir-Catalyzed Selective Hydroboration of 2-Substituted 1,3-Dienes: A General Method to Access Homoallylic Boronates Daniele Fiorito, Clément Mazet* Department of Organic Chemistry, University of Geneva, 30 quai Ernest Ansermet, 1211 Geneva, Switzerland. ABSTRACT: An operationally simple protocol for the 4,3-selective hydroboration of 2-substituted 1,3-dienes using an iridium catalyst is described. Independently of the nature (alkyl, aryl, heteroaryl) and the size of the substituent in the 2position, it provides access to a variety of homoallylic boronates featuring a 1,1-disubstituted olefin in high yield, chemoand regioselectivity. An array of potentially sensitive functional groups is well-tolerated and the method can be extend to 1,2-disubstituted 1,3-dienes. Derivatization of the homoallylic boronates is also demonstrated using contemporary catalytic and enantioselective processes.

KEYWORDS: iridium catalysis, hydroboration, conjugated 1,3-dienes, selective catalysis, homoallylic boronates 3e,3f,4f,7,8

■ INTRODUCTION From a methodology development viewpoint, conjugated 1,3-dienes constitute an attractive platform for selective synthesis and catalysis. Nonetheless, independently of their substitution pattern, functionalizations of conjugated dienes pose challenges both in terms of reactivity (mono- vs. di-functionalization, parasitic reduction, competing isomerization…) and selectivity (chemoselectivity, regioselectivity, diastereoselectivity, enantioselectivity…).1 While linear 1,3-dienes have been often used as a platform for selective catalysis,2 only a limited number of examples have exploited the potential of 2-substituted 1,3-dienes – with a focus restricted to readily available 2-alkyl substituted substrates such as isoprene and myrcene.3 Examples of methods for the selective functionalization of 2-aryl substituted 1,3-dienes are much rarer.4 A simple explanation for this situation may reside in the fact that, until recently, methods to access 2-substituted 1,3-dienes suffered from several impediments.5 Earlier this year, we reported Ni-catalyzed Kumada and Negishi crosscoupling protocols between vinyl magnesium bromide and vinyl phosphates for the preparation of a variety of 2alkyl and 2-aryl 1,3-dienes.6 The methods display a wide functional group tolerance and structurally complex molecular architectures can be readily elaborated. Following this study, we decided to initiate a program on the selective functionalization of 2-substituted 1,3-dienes with an initial emphasis placed on borylation and hydroboration approaches. From a viewpoint of application, allylic and homoallylic boronates are appealing bifunctional building blocks in which both the boronate and the olefin can be extensively and orthogonally manipulated. Importantly, in contrast to allylic boronates, only a few methods have been described for the preparation of homoallylic boronates.

Provided the selectivity challenges are fully addressed, borylation and hydroboration of 2-substituted 1,3-dienes can give access to either allylic boronates (1,4-, 3,4-, 2,1-, 4,1-selectivity) or homoallylic boronates (1,2-, 4,3-selectivity). While Suzuki and co-workers showed that Pd-catalyzed hydroboration of isoprene generated selectively prenyl boronate,3c the Ritter group reported a general Fe-catalyst for the 1,4-selective hydroboration of numerous 2-alkyl substituted 1,3-dienes.3e We recently disclosed a Cu-catalyzed 1,2-borylation of 2-substituted 1,3dienes affording an array of homoallylic boronates featuring a terminal olefin.4f The use of a chiral phosphanamine ligand was found to be crucial in achieving high chemo-, regio-, diastereo- and enantioselectivity. Finally, access to the corresponding isomeric homoallylic boronates with a 1,1-disusbtituted olefin has been achieved either serendipitously by Co-catalyzed hydroboration of myrcene (Chirik)9a and Cu-catalyzed borylation of isoprene (Ito)3f or deliberately by Co-catalyzed hydroboration of isoprene (Fout).9b Given the challenges associated with selective functionalization of 1,3-dienes and the clear lack of a general method to generate homoallylic boronates with a 1,1-di substituted olefin, we set out to identify a catalytic system for the 4,3-selective hydroboration of 2-aryl and 2-alkyl substituted 1,3-dienes. We report herein the successful realization of this objective. ■ RESULTS AND DISCUSSION Reaction optimization. Building upon the antiMarkovnikov selectivity observed with several iridium catalyst in the hydroboration of terminal olefins,10 we began our study by the survey of iridium precursors in combination with mono- and bis-phosphine ligands using myrcene 1a as a model substrate and pinacolborane (Table 1). While, PCy3 and CPhos led to complex mixtures

ACS Paragon Plus Environment

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

Figure 1. (A) General structure of 2-substituted 1,3-dienes and naturally occurring examples. (B) Selectivity challenge in the borylation of 2-substituted 1,3-dienes. (C) Literature precedents. (D) Ir-catalyzed 4,3-selective hydroboration of 2substituted 1,3-dienes. Table 1. Reaction optimizationa

b

b

entry

ligand

solvent

conv. 2a (%)

1

none

CH2Cl2

25:1

10

dppe

THF

76

dppe

j

11 a

THF

94(80) b

>25:1 k

>25:1 1

Reaction conditions: 1a (0.3 mmol). Determined by H NMR of the e crude reaction mixture. c Not determined. d 10 mol%. 2f dicyclohexylphosphino-2′,6′-bis-(N,N-dimethylamino)biphenyl. dppBz: 1,2-bis-(diphenylphosphino)benzene. g dppm: 1,2-bish (diphenylphosphino)methane. dpce: 1,2-bisi (dicyclohexylphosphino)ethane. dppe: 1,2-bis(diphenylphosphino)ethane. j 2.0 equiv. HBpin. k In parenthesis, isolated yield of 2a after purification by column chromatography.

consisting of several isomeric hydroboration products, reduced dienes and boronates, chelating ligands generated quasi-exclusively homoallylic boronate 2a and allylic boronate 3a - the products of formal 4,3- and 4,1hydroboration respectively - in nearly equimolar amount (Entry 4-6). Among these ligands, the commercially available 1,2-bis(diphenylphosphino)ethane (dppe) provided the highest selectivity in favor of the targeted homoallylic boronate 2a (Entry 7). Additional optimization of the reaction conditions enabled to further improve the yield and selectivity and boronate 2a could be isolated in 80% yield, essentially as the sole product of the reaction (2a:3a >25:1). Of important note, no hydroboration of the prenyl chain of 1a was observed, underscoring the high level of chemoselectivity achieved with the final protocol. Products of polyhydroboration were not detected either. Lastly, preliminary evaluation of related systems based on the use of group IX transition metal complexes did not prove successful (See Supporting Information). Reaction scope. The scope of 2-alkyl substituted 1,3dienes was delineated using the optimal conditions developed for myrcene in order to rely on a unified and operationally simple protocol (Figure 2). The products of formal 4,3- hydroboration were isolated in yields ranging from 55% to 82% with excellent chemo- and site selectivity (2a-2j, 10 examples, average yield = 71%). Most conversions were approximating 80-85% and full consumption of the conjugated 1,3-dienes was usually observed, suggesting the borylated products might partially decompose during purification by silica gel chromatography.

ACS Paragon Plus Environment

Page 2 of 7

Page 3 of 7 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

Figure 2. 4,3-Selective hydroboration of 2-alkyl substituted 1,3-dienes (0.3-2.5 mmol scale). Selectivity determined by 1H NMR analysis of the crude reaction mixture. Yields of analytically pure homoallylic boronate 2 after purification by column chromatography. a [IrCl(COD)]2 (5.0 mol%), dppe (10 mol%).

Figure 3. 4,3-Selective hydroboration of 2-(hetero)aryl substituted 1,3-dienes (0.3-0.6 mmol scale). Selectivity determined by 1H NMR analysis of the crude reaction mixture. Yields of analytically pure homoallylic boronate 2 after purification by column chromatography. a 16 h. b 4 h. Conjugated dienes with a primary, a secondary and even a tertiary 2-alkyl substituent were all competent and a variety of potentially reactive functional groups were tolerated (i.e. amine, alkoxy, silyloxy, alkene). More specifically, isolated olefins were found to be compatible with this catalytic method as they were not hydroborated, reduced or isomerized (2a, (Z)-2g, 2i, 2j). The system retains the stereochemistry of a neighboring stereocenter (2h) and is compatible with stereochemically complex scaffold (2i-j). Using the same protocol, substrates with a 2(hetero)aryl substituent were investigated next (Figure 3). Overall, this sub-class of 1,3-dienes underwent hydroboration with high levels of 4,3-selectivity. Unlike 2-alkyl substituted 1,3-dienes, in most cases the main side product resulted from 1,4 hydroboration (4k-u) (13 examples; 63% average yield). Whereas substrates containing electronrich, neutral and poor aromatic substituents were reacted with comparable efficiency, heteroaryl-containing dienes

Figure 4. Hydroboration of 1,2-disubstituted 1,3-dienes (0.15-0.3 mmol). Selectivity determined by 1H NMR analysis of the crude reaction mixture. Yields of analytically pure homoallylic boronate 2 after purification by column chromatography. a Along with 5% of over reduced product. b 16 h. c [IrCl(COD)]2 (5 mol%), dppe (10 mol%).

ACS Paragon Plus Environment

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

Figure 5. Representative derivations of homoallylic boronates. (A) Zweifel olefination. (B) Ir-catalyzed hydroboration. (C) Pd-catalyzed Suzuki cross-coupling. (D) Oxidation/Ir-catalyzed isomerization sequence. (E) Ir-catalyzed enantioselective hydrogenation. led to slightly diminished yields (2t-u, 2w). For substrates with a -extended system (2v-w), the catalyst appeared less selective and products resulting from a hydroboration/isomerization sequence (5v, 5w) and/or from double hydroboration (6w) were also observed. Despite the overall wide scope of application of the present catalytic method, several sensitive functional groups were found to be incompatible (1x-z). To further explore the potential of the present catalytic method, a handful of functionalized diversely substituted 1,3-dienes was also evaluated (Figure 4). It is interesting to note that while 9-BBN is not necessarily the best choice to access homoallylboranes using 2-substituted 1,3dienes,3a,b it was found to be highly selective in the hydroboration of certain 1,2-disubstituted 1,3-dienes11 For instance, (Z)-configured dienyl trimethylsilane 1a’ and (E)-configured dienoate 1e’ were hydroborated without isomerization of the functionalized trisubstituted C=C bond and led to highly 3,4-selective reactions. In both cases only traces of the product of 1,4-hydroboration were detected (>25:1) and the desired homoallylic boronates were isolated in 81% and 40% respectively. Similarly, 4vinyl-1,2-dihydronaphthalene 1c’ delivered 2c’ in 70% yield and exquisite selectivity. In contrast, linear 1,3-diene 1b’, butadiene 1d’, 2,3-disubstituted diene 1f’ and 2,4disubtituted diene 1g’ were not compatible substrates with the protocol developed in this study. Collectively, these results further highlight the strong influence the substitution pattern of 1,3-dienes may exert on the selective outcome of any given transformation.

Derivatizations. In contrast to allylic boronates, only a few methods have been described for the preparation of homoallylic boronates. Consequently, their use in synthesis has been explored to a much lesser extent. A series of possible derivatizations that unveils some of the potential of this building block in organic synthesis is disclosed in Figure 5. For instance, Zweifel olefination of 2a using (vinyl)MgBr and I2 proved as efficient as for related boronates and 1,5-diene 7a was isolated in 67% yield.12 Recent cross-coupling methods are also applicable as 8a was generated in 71% using a protocol developed by Steel, Marder, Liu and coworkers.13 Both direct and sequential double hydroboration of 2-substituted 1,3-dienes appeared difficult to achieve with the Ir/dppe combination described in this study. Nonetheless, we found that switching to 1,2-bis-(diphenylphosphino)methane (dppm) and CH2Cl2, chemoselective hydroboration of allylic boronate 2a was feasible, thus delivering 6a in 71% yield.10c When the Pfaltz-modified version of Crabtree’s catalyst was employed for the isomerization of -geraniol 9a (itself generated by oxidation of 2a), conjugated diene (E)-11a was obtained as the major product of the reaction together with a minimal amount of aldehyde 10a (10a:11a = 15:85).5d,14,15 This result is unexpected because allylic alcohols are typically isomerized quantitatively into aldehydes under these reaction conditions.14c Lastly, Ircatalyzed enantioselective hydrogenation of homoallylic boronates 2a’ and 2c’ afforded 12a’ and 12c’ in excellent yield and high enantiomeric excess (94%, 86% ee; 88%, 84% ee respectively).16

ACS Paragon Plus Environment

Page 4 of 7

Page 5 of 7 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 ■ CONCLUSIONS We have developed a catalytic method for the highly 4,3selective hydroboration of 2-substituted conjugated dienes based on the combination of a commercially available bis-phosphine ligand and a common iridium precursor. The system is robust, practical and applicable to a wide range of 2-alkyl, 2-aryl and 2-heteroaryl 1,3-dienes. It is also compatible with an array of functional groups, sterically demanding environments and stereochemically complex scaffolds. Overall, while our approach further extends the portfolio of catalytic and selective transformations using 2-substituted 1,3-dienes, it also simplifies access to homoallylic boronates featuring a 1,1disubstituted olefin moiety – a building block which bears potential to find widespread application in synthesis.

ASSOCIATED CONTENT Supporting Information. Experimental procedures, characterization of all new compounds and spectral data. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author * Prof. Clément Mazet. University of Geneva, Organic Chemistry Department. Quai Ernest Ansermet 30, Geneva 1211 Switzerland. [email protected]

Notes The authors declare no competing financial interests.

ACKNOWLEDGMENT We thank the University of Geneva and the Swiss Chemical Society for financial support.

REFERENCES (1) (a) Mahatthananchai, J.; Dumas, A. M.; Bode, J. W. Catalytic Selective Synthesis. Angew. Chem., Int. Ed. 2012, 51, 10954−10990. (b) Huang, Z.; Dong, G. Site-Selectivity Control in Organic Reactions: A Quest To Differentiate Reactivity among the Same Kind of Functional Groups. Acc. Chem. Res. 2017, 50, 465−471. (2) Xiong, Y.; Sun, Y.; Zhang, G. Recent Advances on Catalytic Asymmetric Difunctionalization of 1,3-Dienes. Tetrahedron Lett. 2018, 59, 347−355. (3) (a) Zweifel, G.; Nagase, K.; Brown, H. C. Hydroboration. XIII. The Hydroboration of Dienes with Disiamylborane. A Convenient Procedure for the Conversion of Selected Dienes into Unsaturated Alcohols. J. Am. Chem. Soc. 1962, 84, 190−195. (b) Brown, H. C.; Singh, K. P.; Garner, B. J Hydroboration of Terpenes I. The Selective Hydroboration of Myrcene with Disiamylborane J. Organomet. Chem. 1963, 1, 2−7. (c) Satoh, M.; Nomoto, Y.; Miyaura, N.; Suzuki, A. New Convenient Approach to the Preparation of (Z)-Allylic Boronates via Catalytic 1,4Hydroboration of 1,3-Dienes with Catecholborane. Tetrahedron Lett. 1989, 30, 3789−3792. (d) Zaidlewicz, M.; Meller, J. Syntheses with Organoboranes. VII. Monohydroboration of Conjugated Dienes with Catecholborane Catalyzed by Complexes of Nickel(II) Chloride and Cobalt(II) Chloride with Diphosphines. Tetrahedron Lett. 1997, 38, 7279−7282. (e) Wu, J. Y.; Moreau, B.; Ritter, T. Iron-Catalyzed 1,4-Hydroboration of 1,3-Dienes. J. Am. Chem. Soc. 2009, 131, 12915−12917. (f) Sasaki, Y.; Zhong, C.;

Sawamura, M.; Ito, H. Copper(I)-Catalyzed Asymmetric Monoborylation of 1,3-Dienes: Synthesis of Enantioenriched Cyclic Homoallyl- and Allylboronates. J. Am. Chem. Soc. 2010, 132, 1226−1227. (g) Ebe, Y.; Nishimura, T. Iridium-Catalyzed Annulation of Salicylimines with 1,3-Dienes. J. Am. Chem. Soc. 2014, 136, 9284−9287. (h) McCammant, M. S.; Sigman, M. S. Development and Investigation of a Site Selective Palladium-Catalyzed 1,4Difunctionalization of Isoprene Using Pyridine–Oxazoline Ligands. Chem. Sci. 2015, 6, 1355−1361. (i) Hoyt, J. M.; Schmidt, V. A.; Tondreau, A. M.; Chirik, P. J. Iron-Catalyzed Intermolecular [2+2] Cycloadditions of Unactivated Alkenes. Science 2015, 349, 960−963. (j) Jiang, L.; Cao, P.; Wang, M.; Chen, B.; Wang, B.; Liao, J. Highly Diastereo- and Enantioselective Cu-Catalyzed Borylative Coupling of 1,3-Dienes and Aldimines. Angew. Chem., Int. Ed. 2016, 55, 13854−13858. (k) Li, X.; Meng, F.; Torker, S.; Shi, Y.; Hoveyda, A. H. Catalytic Enantioselective Conjugate Additions of (pin)B-Substituted Allylcopper Compounds Generated in situ from Butadiene or Isoprene. Angew. Chem., Int. Ed. 2016, 55, 9997−10002. (l) Raya, B.; Jing, S.; RajanBabu, T. V. Control of Selectivity through Synergy between Catalysts, Silanes and Reaction Conditions in Cobalt-Catalyzed Hydrosilylation of Dienes and Terminal Alkenes. ACS Catalysis 2017, 7, 2275−2283. (m) Smith, K. B.; Brown, M. K. Regioselective Arylboration of Isoprene and Its Derivatives by Pd/Cu Cooperative Catalysis. J. Am. Chem. Soc. 2017, 139, 7721−7724. (n) Shen, H.-C.; Wu, Y.-F.; Zhang, Y.; Fan, L.-F.; Han, Z.-Y.; Gong, L.-Z. Palladium-Catalyzed Asymmetric Aminohydroxylation of 1,3-Dienes. Angew. Chem., Int. Ed. 2018, 57, 2372−2376. (o) Smith, K. B.; Huang, Y.; Brown, M. K. Copper-Catalyzed Heteroarylboration of 1,3-Dienes with 3Bromopyridines: A cine Substitution. Angew. Chem. Int. Ed. 2018, 57, 6146−6149. (p) Schmidt, V. A.; Kennedy, C. R.; Bezdek, M. J.; Chirik, P. J. Selective [1,4]-Hydrovinylation of 1,3-Dienes with Unactivated Olefins Enabled by Iron Diimine Catalysts. J. Am. Chem. Soc., 2018, 140, 3443−3453. (4) (a) Smejkal, T.; Han, H.; Breit, B.; Krische, M. J. All-Carbon Quaternary Centers via Ruthenium-Catalyzed Hydroxymethylation of 2-Substituted Butadienes Mediated by Formaldehyde: Beyond Hydroformylation. J. Am. Chem. Soc. 2009, 131, 10366−10367. (b) Chen, Q.-A.; Kim, D. K.; Dong, V. M. Regioselective Hydroacylation of 1,3-Dienes by Cobalt Catalysis. J. Am. Chem. Soc. 2014, 136, 3772−3775. (c) Nguyen, K. D.; Herkommer, D.; Krische, M. J. Enantioselective Formation of All-Carbon Quaternary Centers via C−H Functionalization of Methanol: IridiumCatalyzed Diene Hydrohydroxymethylation. J. Am. Chem. Soc. 2016, 138, 14210−14213. (d) Oda, S.; Franke, J.; Krische, M. J. Diene Hydroaminomethylation via Ruthenium catalyzed C–C Bond Forming Transfer Hydrogenation: Beyond Carbonylation. Chem. Sci. 2016, 7, 136−141. (e) Yang, X.-H.; Lu, A.; Dong, V. M. Intermolecular Hydroamination of 1,3-Dienes To Generate Homoallylic Amines. J. Am. Chem. Soc. 2017, 139, 14049−14052. (f) Liu, Y.; Fiorito, D.; Mazet, C. Copper-Catalyzed Enantioselective 1,2Borylation of 1,3-Dienes. Chem. Sci. 2018, 9, 5284−5288. (5) (a) Nunomoto, S.; Kawakami, Y.; Yamashita, Y. Synthesis of 2-Substituted 1,3-Dienes by Cross-Coupling Reaction of 2-(1,3butadienyl)magnesium Chloride with Alkyl or Aryl Iodide. Bull. Chem. Soc. Jpn. 1981, 54, 2831−2832. (b) Sahlberg, C.; Quader, A.; Claesson, A. Synthesis of Conjugated Dienes by Nickel Catalyzed Reactions of 1,3-Alkadien-2-yl Phosphates with Grignard Reagents. Tetrahedron Lett. 1983, 24, 5137−5138. (c) Tonogaki, K.; Mori, M. An Improved 1,3-Diene Synthesis from Alkyne and Ethylene Using Cross-Enyne Metathesis. Tetrahedron Lett. 2002, 43, 2235−2238. (d) Li, H.; Fiorito, D.; Mazet, C. Exploring Site Selectivity of Iridium Hydride Insertion into Allylic Alcohols: Serendipitous Discovery and Comparative Study of Organic and Organometallic Catalysts for the Vinylogous Peterson Elimination. ACS Catal. 2017, 7, 1554−1562.

ACS Paragon Plus Environment

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

(6) Fiorito, D.; Folliet, S.; Liu, Y.; Mazet, C. A General NickelCatalyzed Kumada Vinylation for the Preparation of 2‑ Substituted 1,3-Dienes. ACS Catal. 2018, 8, 1392−1398. (7) (a) Hall, D. G.; Lachance, H. Allylboration of Carbonyl Compounds; Wiley: Hoboken, NJ, 2012. (b) Diner, C.; Szabò, K. J. Recent Advances in the Preparation and Application of Allylboron Species in Organic Synthesis. J. Am. Chem. Soc. 2017, 139, 2−14. (8) (a) Fletcher, C. J.; Blair, D. J.; Wheelhouse, K. M. P.; Aggarwal, V. K. The Total Synthesis of ()-Aplysin via a LithiationBorylationPropenylation Sequence. Tetrahedron 2012, 68, 7598−7604. (b) Endo, K.; Ohkubo, T.; Ishioka, T.; Shibata, T. Cross Coupling between sp3-Carbon and sp3-Carbon Using a Diborylmethane Derivative at Room Temperature J. Org. Chem. 2012, 77, 4826−4831. (c) Semba, K.; Shinomiya, M.; Fujihara, T.; Terao, J.; Tsuji, Y. Highly Selective Copper-Catalyzed Hydroboration of Allenes and 1,3-Dienes. Chem. Eur. J. 2013, 19, 7125−7132. (d) Zhang, Z.- Q.; Yang, C.- T.; Liang, L.- J.; Xiao, B.; Lu, X.; Liu, J.-H.; Sun, Y.-Y.; Marder, T. B.; Fu, Y. CopperCatalyzed/Promoted Cross-Coupling of Gem-Diborylalkanes with Nonactivated Primary Alkyl Halides: An Alternative Route to Alkylboronic Esters. Org. Lett. 2014, 16, 6342−6345. (e) Sušnik, P.; Hilt, G. Homoallylpinacolboronic Ester as Alkene Component in Cobalt-Catalyzed Alder Ene Reactions. Organometallics 2014, 33, 5907−5910. (f) Pujol, A.; Calow, A. D. J.; Batsanov, A. S.; Whiting, A. One-Pot Catalytic Asymmetric Borylation of Unsaturated Aldehyde-Derived Imines; Functionalisation to Homoallylic Boronate Carboxylate Ester Derivatives. Org. Biomol. Chem. 2015, 13, 5122−5130. (g) Kim, J.; Park, S.; Park, J.; Cho, S. H. Synthesis of Branched Alkylboronates by Copper-Catalyzed Allylic Substitution Reactions of Allylic Chlorides with 1,1Diborylalkanes. Angew. Chem., Int. Ed. 2016, 55, 1498−1501. (h) Shi, Y.; Hoveyda, A. H. Catalytic SN2’- and Enantioselective Allylic Substitution with a Diborylmethane Reagent and Application in Synthesis. Angew. Chem., Int. Ed. 2016, 55, 3455−3458. (i) Zhan, M.; Li, R.-Z.; Mou, Z.-D.; Cao, C.-G.; Liu, J.; Chen, Y.-W.; Niu, D. Silver-Assisted, Iridium-Catalyzed Allylation of Bis[(pinacolato)boryl]-methane Allows the Synthesis of Enantioenriched Homoallylic Organoboronic Esters. ACS Catal. 2016, 6, 3381−3386. (j) Han, J. T.; Jang, W. J.; Kim, N.; Yun, J. Asymmetric Synthesis of Borylalkanes via Copper-Catalyzed Enantioselective Hydroallylation J. Am. Chem. Soc. 2016, 138, 15146−15149. (k) Lee, J.; Torker, S.; Hoveyda, A. H. Versatile Homoallylic Boronates by Chemo-, SN2’-, Diastereo- and Enantioselective Catalytic Sequence of CuH Addition to Vinyl-B(pin)/Allylic Substitution. Angew. Chem., Int. Ed. 2017, 56, 821−826. (l) Li, C.; Li, M.; Li, J.; Wu, W.; Jiang, H. Palladium-Catalyzed Oxidative Allylation of Bis[(pinacolato)boryl]methane: Synthesis of Homoallylic Boronic Esters. Chem. Commun. 2018, 54, 66−69. (9) (a) Obligacion, J. V.; Chirik, P. J. Bis(imino)pyridine Cobalt-Catalyzed Alkene Isomerization−Hydroboration: A Strategy for Remote Hydrofunctionalization with Terminal Selectivity. J. Am. Chem. Soc. 2013, 135, 19107−19110. (b) Ibrahim, A. D.; Entsminger, S. W.; Fout, A. R. Insights into a Chemoselective Cobalt Catalyst for the Hydroboration of Alkenes and Nitriles. ACS Catal. 2017, 7, 3730−3734. (10) (a) Westcott, S. A.; Marder, T. B.; Baker, R. T. TransitionMetal-Catalyzed Addition of Catecholborane to -Substituted Vinylarenes: Hydroboration vs Dehydrogenative Borylation. Organometallics 1993, 12, 975−979. (b) Crudden, M. C.; Hleba, Y. B.; Chen A. C. Regio- and Enantiocontrol in the RoomTemperature Hydroboration of Vinyl Arenes with Pinacol Borane. J. Am. Chem. Soc. 2004, 126, 9200−9201. (c) Yamamoto, Y.; Fujikawa, R.; Umemoto, T; Miyaura, N. Iridium-Catalyzed Hydroboration of Alkenes with Pinacolborane. Tetrahedron 2004, 60, 10695−10700. (d) Cipot, J.; Vogels, C. M.; McDonald, R.;

Westcott, S. A.; Stradiotto, M. Catalytic Alkene Hydroboration Mediated by Cationic and Formally Zwitterionic Rhodium(I) and Iridium(I) Derivatives of a P,N-Substituted Indene. Organometallics 2006, 25, 5965−5968. (e) Gérard, D.; Mazet, C. Highly Regio- and Enantioselective Catalytic Asymmetric Hydroboration of -Substituted Styrenyl Derivatives. Chem. Commun. 2011, 47, 298−300. (f) Lee, G. M. ; Vogels, C. M.; Decken, A.; Westcott, S. A. Iridium Phosphane Complexes Containing Arylspiroboronate Esters for the Hydroboration of Alkenes. Eur. J. Inorg. Chem. 2011, 2433−2438. (g) Magre, M.; Biosca, M.; Pàmies, O.; Diéguez, M. Filling the Gaps in the Challenging Asymmetric Hydroboration of 1,1‐Disubstituted Alkenes with Simple Phosphite‐Based Phosphinooxazoline Iridium Catalysts. ChemCatChem 2015, 7, 114−120. (11) Kallan, N. C.; Halcomb, R. L. Synthesis of the Ring System of Phomactin D Using a Suzuki Macrocyclization. Org. Lett. 2000, 2, 2687−2690. (12) Armstrong, R. J.; Aggarwal, V. K. 50 Years of Zweifel Olefination: A Transition-Metal-Free Coupling. Synthesis 2017, 49, 3323−3336. (13) Yang, C.-T.; Zhang, Z.-Q.; Tajuddin, H.; Wu, C.-C.; Liang, J.; Liu, J.-H.; Fu, Y.; Czyzewska, M.; Steel, P. G.; Marder, T. B.; Liu, L. Alkylboronic Esters from Copper-Catalyzed Borylation of Primary and Secondary Alkyl Halides and Pseudohalides. Angew. Chem., Int. Ed. 2012, 51, 528−532. (14) (a) Crabtree, R. H. Iridium Compounds in Catalysis. Acc. Chem. Res. 1979, 12, 331−337. (b) Wüstenberg, B.; Pfaltz, A. Homogeneous Hydrogenation of Tri‐ and Tetrasubstituted Olefins: Comparison of Iridium‐Phospinooxazoline [Ir‐PHOX] Complexes and Crabtree Catalysts with Hexafluorophosphate (PF6) and Tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (BArF) as Counterions. Adv. Synth. Catal. 2008, 350, 174−178. (15) (a) Mantilli, L.; Mazet, C. Iridium-Catalyzed Isomerization of Primary Allylic Alcohols Under Mild Reaction Conditions. Tetrahedron Lett. 2009, 50, 4141−4144. (b) Li, H.; Mazet, C. Steric Parameters in the Ir-Catalyzed Regio- and Diastereoselective Isomerization of Primary Allylic Alcohols. Org. Lett. 2013, 15, 6170−6173. (c) Li, H.; Mazet, C. Iridium-Catalyzed Selective Isomerization of Primary Allylic Alcohols. Acc. Chem. Res. 2016, 49, 1232−1241. (16) (a) Kaiser, S.; Smidt, S. P.; Pfaltz, A. Iridium Catalysts with Bicyclic Pyridine–Phosphinite Ligands: Asymmetric Hydrogenation of Olefins and Furan Derivatives. Angew. Chem., Int. Ed. 2006, 45, 5194−5197. (b) Roseblade, S. J.; Pfaltz, A. IridiumCatalyzed Asymmetric Hydrogenation of Olefins. Acc. Chem. Res. 2007, 40, 1402−1411. (c) Wang, A.; Bernasconi, M.; Pfaltz, A. Iridium-Catalyzed Enantioselective Hydrogenation of Vinylsilanes. Adv. Synth. Catal. 2017, 359, 2523−2529.

ACS Paragon Plus Environment

Page 6 of 7

Page 7 of 7 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

TOC

ACS Paragon Plus Environment