Symmetric and unsymmetric 3,3′-linked bispyrroles via ring-enlargement reactions of furan-derived donor–acceptor cyclopropanes
作者:Johannes Kaschel、Tobias F. Schneider、Daniel Kratzert、Dietmar Stalke、Daniel B. Werz
DOI:10.1039/c3ob40228b
日期:——
A short and concise sequence for the synthesis of symmetrically and unsymmetrically substituted 3,3′-linked bispyrroles is described. Furan as a starting material is subjected to a twofold cyclopropanation by a diazo ester. Conversion of the ester functionalities to the respective ketones is achieved via Weinreb amide formation and the attack of a Grignard reagent. In the presence of amines the ketone
描述了用于合成对称和不对称取代的3,3'-连接的双吡咯的短而简洁的序列。以重氮为原料,将呋喃作为起始原料进行两次环丙烷化。通过Weinreb酰胺的形成和格氏试剂的攻击,将酯官能度转化为相应的酮。在胺存在下,酮部分形成亚胺,其通过将三元环扩大到五元环而重排。原位产生的二氢吡咯部分除去水并提供芳族吡咯单元。不对称的双吡咯是通过在胺的添加引发级联到各个双吡咯之前,使用不同的环丙烷化剂或改变格氏试剂来形成酮而获得的。