在Li +存在下和在水存在或不存在PTC的情况下,进行酮和醛的反应以生成醛醇产物。已经证明了水性反应相对于有机溶剂介导的反应的几个优点,包括更高的产率,更短的反应时间,更简单的纯化以及更好的官能团耐受性。在水中已经实现了一些在有机溶剂中不发生的反应。成功归因于相邻的杂原子效应。在水性羟醛缩合中,Li 2 CO 3硫醇是一种有效的催化剂,因此可与碱结合的基团(例如环氧化物,酯和甲硅烷基)可以幸免。对于杂芳族乙酮,在没有PTC的情况下完成了水性醛醇缩合反应,以良好的收率得到了β-羟基酮。水介导的醛基半缩醛与芳香族酮的缩合导致定量产率的新的碳水化合物衍生骨架。在某种程度上,这项研究扩大了醛醇缩合和反应的适用性。
Abstract A facile synthesis of novel dispiro oxindole-pyrrolothiazole-androsterone hybrid heterocycles has been achieved through 1,3-dipolarcycloaddition. The reaction proceeds stereo- and regioselectively, affording a single isomer of the product in excellent yields with the formation of two C–C and one C–N bonds and creation of four new contiguous stereocenters in one step. GRAPHICAL ABSTRACT
The 1,3-dipolar cycloaddition of azomethine ylide derived in situ from the reaction of acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from trans-androsterone and trans-dehydroandrosterone afforded a library of novel spiro[5'.2 '']acenaphthylene-1 ''-one-spiro[16.6']-(7'-aryl)-tetrahydro-1H-pyrrolo [1,2-c][1,3]thiazolo-trans-androsterone/dehydroandrosterone hybrid heterocycles respectively. These reactions proceeded stereo-specifically affording a single isomer of the 16-spiro steroids in excellent yields. (C) 2013 Elsevier Inc. All rights reserved.