Lewis acid catalyzed asymmetric halohydrin reactions of chiral α,β-unsaturated carboxylic acid derivatives with N-halosuccinimide (NXS) as the halogen source
作者:Saumen Hajra、Manishabrata Bhowmick、Ananta Karmakar
DOI:10.1016/j.tetlet.2005.03.014
日期:2005.4
Lewis acid catalyzed asymmetric halohydrin reactions—(halohydroxylation as well as halomethoxylation) of chiral α,β-unsaturated carboxylic acid derivatives were performed using N-halosuccinimide (NXS; X = Br, I) as the halogen source. Regio- and anti-selectivity of 100% and moderate to good diastereoselectivity with good yields were observed when Oppolzer’s sultam was used as the chiral auxiliary.
使用N-卤代琥珀酰亚胺(NXS; X = Br,I)作为卤素源,进行路易斯酸催化的手性α,β-不饱和羧酸衍生物的不对称卤代醇反应(卤代羟基化以及卤代甲氧基化)。当Oppolzer的sultam用作手性助剂时,观察到区域选择性和抗选择性为100%,中等至良好的非对映选择性,并具有良好的收率。路易斯酸中,Yb(OTf)3被发现是最好的催化剂。烯酰基和肉桂酰基底物顺利地进行了溴代醇反应,较富电子的肉桂酰基底物优选经历了碘代醇反应。但是,缺电子的肉桂酰基底物不响应此路易斯酸催化的NXS与卤代醇反应(X = Cl,Br,I)。