Design of a Nonreductive Method for Chemoselective Cleavage of Hydrazines in the Presence of Unsaturations: Application to a Stereoconvergent Three-Component Synthesis of (−)-Methyl Palustramate
作者:Barry B. Touré、Dennis G. Hall
DOI:10.1021/jo048581o
日期:2004.11.1
a mild acid-promoted fragmentation of tetrasubstituted 1-(trimethylsilylmethyl)-1-benzylhydrazines. This strategy was applied to a concise asymmetric synthesis of (−)-methyl palustramate (4), which featured a convergent stereo- and regioselective sequential three-component aza[4+2]cycloaddition/allylboration/retro-sulfinyl-ene rearrangement between diene 1f, dienophile 2b, and propionaldehyde to afford
基于四取代的1-(三甲基甲硅烷基甲基)-1-苄基肼的温和酸促进的裂解,开发了保留烯烃完整性的化学选择性肼(NN)裂解方法。该策略适用于简明的不对称合成(-)-甲基草酸酯(4),其特征是二烯之间的立体和区域选择性顺序三组分氮杂[4 + 2]环氮杂[4 + 2]环加成/烯丙基化/亚硫酰-烯重排1f,亲二烯体2b和丙醛,得到顺-2-羧基-6-羟烷基哌啶25。用酸促进的肼分解反应得到25种干净得到的关键中间体31,在一系列功能组转换后,后者分四个步骤实现了目标4。