It is well known that pyridinium
N-ylides and their relating pyridinium salts are very useful precursors for the syntheses of some nitrogen-bridged heterocycles, especially, indolizine and pyrazolo [1, 5-
a] pyridine. The conventional preparative methods such as the 1, 3-dipolar cycloaddition and the 1, 5-dipolar cyclization of pyridinium
N-ylides, and Tschitschibabin reactions of 1-acylmethyl-2-alkyl or aralkylpyridinium salts are convenient to the syntheses of their derivatives, but the compounds obtained thus are helpless for further transformation to fused indolizines and pyrazolo [1, 5-
a] pyridines except a few examples. This article describes novel preparative methods for some functionalized indolizines and pyrazolo [1, 5-
a] pyridines and their transformation to new fused heterocycles using their functionality.
抄録全体を表示