Access to Enantioenriched Benzylic 1,1-Silylboronate Esters by Palladium-Catalyzed Enantiotopic-Group Selective Suzuki–Miyaura Coupling of (Diborylmethyl)silanes with Aryl Iodides

Abstract

This work describes the palladium-catalyzed enantiotopic-group selective Suzuki–Miyaura cross-coupling of (diborylmethyl)­silanes with aryl iodides. The combination of a Pd­(TFA)2 and rev-Josiphos-type ligand bearing a 3,5-bis­(trifluoromethyl)­phenyl as benzylic phosphine substituent in the presence of NaI as an additive and NaOMe as a base promotes the reaction to high efficiency and enantioselectivity. This method provides a convenient approach for synthesizing chiral benzylic 1,1-silylboronate esters from readily accessible reagents. Synthetic applications including stereospecific C–O, C–N, and C–C bond-forming reactions of boron group are also demonstrated.

Selective C−C Coupling of Vinyl Epoxides with Diborylmethide Lithium Salts

“…Remarkably, when the geminal diborylalkane reagents contained an alkyl group instead of an aryl group, their reaction with 1 showed the regioselective S N 2 ring opening/C−C coupling, but only one exclusive diastereoisomer was formed along the H‐deborylative process (Table ). Reagents, such as (2‐phenylethane‐1,1‐diyl)bis(pinacolborane) ( 20 ) and (3‐phenylpropane‐1,1‐diyl)bis(pinacolborane) ( 22 ), generated the products 21 and 23 in moderate yields as a sole diastereoisomer (Table , entries 1, 2), whereas reagents octane‐1,1‐diylbis(dimethylborane) ( 24 ) and [bis(pinacolboranyl)methyl]trimethylsilane ( 26 ) contributed to higher isolated yields of the single diastereoisomers 25 and 27 , (Table , entries 3, 4) being the last one full characterized by X‐ray diffraction (Figure ). Interestingly, the fact that protodeboronation reaction can be stereoselective when an alkyl group is attached to the diborylmethide lithium salt is in agreement with a recent observation in diastereoselective protodeboronation between 1,1‐diborylalkanes and N‐tert ‐butanesulfinyl aldimines …”

Regio‐controllable Cobalt‐Catalyzed Sequential Hydrosilylation/Hydroboration of Arylacetylenes

“…Among them, silylboronates are unique and useful ones due to their high stability and versatile transformable manner (Scheme 1 a). [4d,f] Accordingly, several methods have been developed for the synthesis such as alkene silaboration, [5] vinylsilane hydroboration, [6, 15] vinylboronate hydrosilylation, [7] Suzuki–Miyaura coupling, [8] etc [4d,f, 9] . Despite the advances, most of these methodologies afford the products bearing silyl groups without Si−H bond, [6b,c] which would diminish their further elaborations [10] .…”

Preparing Pd catalysts based on urea ligand via electrospinning for Suzuki–Miyaura cross‐coupling reactions

“…[1][2][3] In recent years, SMC reactions have been studied widely and have made significant progress. [4][5][6][7][8][9][10] Literature reveals that palladium is often regarded as the principal catalyst for SMC reactions, [11] whose traditional mechanism generally includes oxidation addition reaction (OAR), transmetalation, and reduction elimination reaction. In general, OAR is often regarded as the rate-determining step; [12][13][14] thus, researchers are pursuing several approaches to reduce its activation energy, speeding up the whole reaction.…”