A New Two-Step Preparation of Pyrroles from β-Amino Ketones Utilizing Trimethylsilyldiazomethane
作者:Tsutomu Yagi、Toyohiko Aoyama、Takayuki Shioiri
DOI:10.1055/s-1997-1552
日期:1997.9
Lithium trimethylsilyldiazomethane smoothly reacted with N-substituted β-amino ketones to give 2-pyrrolines which were easily converted to the corresponding pyrroles by treatment with MnO2 (CMD, chemical manganese dioxide). The reaction with N,N-disubstituted β-amino ketones followed by oxidation with CMD also afforded pyrroles.
A general and regioselective synthesis of substituted pyrroles 2 by cycloisomerization of readily available (Z)-(2-en-4-ynyl)amines 1 is reported. Spontaneous cycloisomerization leading to 2 occurred in the course of preparation of enynamines bearing a terminal triple bond or a triple bond substituted with a phenyl or a CH2OTHP group. When the triple bond was substituted with an alkyl or alkenyl group