Asymmetric addition of phenylzinc reagents to C-alkynyl nitrones. Enantiomeric enhancement by a product-like additive
摘要:
Asymmetric addition of diphenylzinc to C-alkynyl nitrones was achieved by utilizing di(t-butyl) (R,R)-tartrate as a chiral auxiliary to afford the corresponding optically active (S)-N-(1-phenyl-3-substituted prop-2-ynyl)hydroxylamines. By the addition of a product-like additive, enantiomeric enhancement was observed. A mixed zinc reagent, PhZnMe, improved the enantioselection to afford hydroxylamines in up to 92% ee. (C) 2008 Elsevier Ltd. All rights reserved.
The catalytic asymmetricaddition of alkynylzinc reagents, which were prepared in situ from dimethylzinc and 1-alkynes, to nitrones was achieved by utilizing di(t-butyl) (R,R)-tartrate as a chiral ...
The asymmetric addition of alkynylzinc reagents, prepared in situ from dialkylzinc and 1-alkynes, to nitrones was achieved by utilizing di(t-butyl) (R,R)-tartrate as a chiralauxiliary to afford the corresponding optically active (R)-α-substituted propargylic N-hydroxylamines. By the addition of product-like N-hydroxylamine, unprecedented enhancement of enantioselectivity was observed to afford the
由二烷基锌和 1-炔烃原位制备的炔基锌试剂与硝酮的不对称加成是通过使用二(叔丁基)(R,R)-酒石酸盐作为手性助剂来实现的,以提供相应的旋光性(R)- α-取代的炔丙基N-羟胺。通过添加类似产品的 N-羟胺,观察到对映选择性的前所未有的增强,以提供高达 95% ee 的 N-羟胺。