Preparation of silanethiols by reaction of silanes with triphenylphosphine sulfide and with alkanethiols
作者:Yudong Cai、Brian P Roberts
DOI:10.1016/s0040-4039(01)00801-2
日期:2001.7
Silanes react with triphenylphosphine sulfide by a radical-chain mechanism to give the corresponding silanethiols in good yield. Silanethiols are similarly formed when silanes react with tert-dodecanethiol. Enantiomerically pure (S)-ButMePhSiH gave racemic silanethiol with Ph3PS, but with tert-dodecanethiol silanethiol with an ee up to 60% has been obtained, although in low chemical yield.
A convenientaccess to opticallyactive silyl- and germyllithium compounds (tBuMePhELi·sp, E = Si (1), Ge (2)) was accomplished by only addition of (−)-sparteine (abbr. sp) ligand to racemic silyl- and germyllithiums. Opticallyactive silyllithium (1·sp) and germyllithium (2·sp) could be isolated by recrystallization from pentane/toluene mixed solvents. The 1·sp and 2·sp have ‘R’ configuration clearly
Copper(II)-mediated σ-metathesis with prochiral dihydrosilanes has been successfully leveraged to efficiently synthesize Si-chiral silanols as well as many other related Si-chiral skeletons. The reaction hinges on the continuous generation of catalytically active copper(II) species via single-electron transfer oxidation of copper(I) by alkyl halides and the efficient stereocontrol with multidentate
铜 (II) 介导的σ复分解与前手性二氢硅烷已成功用于有效合成 Si-手性硅烷醇以及许多其他相关的 Si-手性骨架。该反应取决于通过卤代烷对铜 (I) 进行单电子转移氧化连续生成具有催化活性的铜 (II),以及使用多齿阴离子 N,N,P-配体进行有效的立体控制。
An enantioselective nucleophilic substitution reaction of achiral dialkoxysilane has been developed. The reaction proceeds with efficient stereocontrol on the silicon chirality center to give the enantioenriched silyl ether, which can be converted to the silanol without loss of enantiopurity. We have analyzed the steric course of the reaction by using DFT calculations and propose a transition state model to explain the observed enantioselectivity.
Facile synthesis of enantiomerically pure tert-butyl(methyl)phenylsilanes
A method for the preparation of both enantiomers of tert-butyl(methyl)phenylsilane 2 is presented. Racemic tert-butyl(methyl)phenylsilyl chloride 3 was allowed to react with (R)-(-)-2-amino-1-butanol 4 to give hydrochloride 5. Diastereomer separation via treatment of the respective free amine 6 with 0.5 mol equivalent of HCl in hexane-2-propanol yielded crystalline diastereomerically pure hydrochloride (R)Si-5. The corresponding free amine (R)Si-6 was reduced with LiAlH4 to give (S)-2. The mother liquors obtained after separation of (R)Si-5 on treatment with oxalic acid provided a crystalline salt that eventually afforded (R)-2. The optical purity of (S)-2 (98% ee) was documented by its reaction (hydrosilylation) with propargylic alcohol derivative 10 and HPLC analysis of product lr using a chiral column. (C) 1999 Elsevier Science Ltd. All rights reserved.