Stereochemically Controlled Asymmetric 1,2-Reduction of Enones Mediated by a Chiral Sulfoxide Moiety and a Lanthanum(III) Ion
摘要:
Enantiomerically pure (Z)-beta-sulfinyl allylic alcohols of either handedness can be readily prepared from (Z)-beta-sulfinyl enones using NaBH4 or DIBAL reductants in the presence of LaCl3 as a chelating agent. A chiral sulfoxide auxiliary induces the remote 1,2-asymmetric reduction (1,4-induction) to afford various chiral allylic alcohols in high yields with excellent stereoselectivities (up to 100% de).
Stereochemically Controlled Asymmetric 1,2-Reduction of Enones Mediated by a Chiral Sulfoxide Moiety and a Lanthanum(III) Ion
摘要:
Enantiomerically pure (Z)-beta-sulfinyl allylic alcohols of either handedness can be readily prepared from (Z)-beta-sulfinyl enones using NaBH4 or DIBAL reductants in the presence of LaCl3 as a chelating agent. A chiral sulfoxide auxiliary induces the remote 1,2-asymmetric reduction (1,4-induction) to afford various chiral allylic alcohols in high yields with excellent stereoselectivities (up to 100% de).
Remote induction of stereoselective 1,2-addition of aryl Grignard reagents to β-sulfinyl enones
作者:Toshinori Nakakita、Motofumi Miura、Masaharu Toriyama、Shigeyasu Motohashi、Mikhail V. Barybin
DOI:10.1016/j.tetlet.2013.12.108
日期:2014.1
Opticallyactive tert-allylic alcohols constitute important and often challenging targets in organic synthesis. In this work, we employed a β-sulfinyl moiety as a remote chiral auxiliary to effect asymmetric 1,2-addition of aryl Grignardreagents to enones to form a variety of opticallyactive tert-allylic alcohols. The absolute configuration of a representative alcohol product was determined by X-ray
The synthesis of optically active secondary and tertiary propargylicalcohols was accomplished by addition of lithium acetylide to chiral β-sulfinyl enones. Only a stoichiometric amount of the lithium acetylide was required and various substituents were tolerated. This reaction could be applied to substrates consisting of both ketones and aldehydes in high yields and excellent diastereoselectivities