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