Enantioselective Platinum‐Catalyzed Silicon‐Boron Addition to 1,3‐Cyclohexadiene

Abstract

Silaboration of 1,3-cyclohexadiene in the presence of Pt(acac) 2 , DIBALH, and a phosphoramidite prepared from (S)-1,1'-bi-2-naphthol and diisopropylamine led to (1R,4S)-1-(dimethylphenylsilyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-cyclohexene with 70% ee. Chiral catalysts based on Ni gave no or essentially racemic product, whereas complexes containing Pd were inactive.

Phosphoramidites: Privileged Ligands in Asymmetric Catalysis

“…Chemie disubstituted cyclohexenes, although the yields and ee values are so far only moderate. [421,422]…”

Transition‐Metal‐Catalyzed Synthesis of Chiral Allylboronates†

“…Platinum complexes ( e.g ., Pt 2 (dba) 3 , Pt(dba) 3 ,) were proved as the most effective (pre)catalysts for the enantioselective diboration of conjugated dienes, by Morken and co‐workers. [ 71‐76 ] Upon the investigation of Pd‐catalyzed diboration of allenes, [ 77‐81 ] chiral TADDOL‐derived phosphoramidites were found to significantly accelerate borylation reactions. [ 71 ] Furthermore, they were also employed as supporting ligands in the Pt‐catalyzed enantioselective diboration of conjugated dienes (Scheme 12).…”

“…[ 71‐76 ] Upon the investigation of Pd‐catalyzed diboration of allenes, [ 77‐81 ] chiral TADDOL‐derived phosphoramidites were found to significantly accelerate borylation reactions. [ 71 ] Furthermore, they were also employed as supporting ligands in the Pt‐catalyzed enantioselective diboration of conjugated dienes (Scheme 12). [ 72 ] This class of ligands has found broad applications in the diboration of cyclic [ 74 ] and 1,3‐dienes.…”

Asymmetric Synthesis of Chiral 1,3‐Disubstituted Allylsilanes via Copper(I)‐Catalyzed 1,4‐Conjugate Silylation of α,β‐Unsaturated Sulfones and Subsequent Julia‐Kocienski Olefination

“…Recently, new strategies with high synthetic efficiency have been emerging. Basically, these strategies are classified into two types, including transformations with organic molecules bearing a pre‐installed silyl group [ 8‐21 ] or introductions of silicon to organic compounds. [ 22‐34 ] In the latter cases, the simultaneous induction of chirality and silicon species under asymmetric catalysis is particularly attractive due to the higher synthetic efficiency.…”