A regioselective synthesis of 5-pyrazolones and pyrazoles from phosphazenes derived from hydrazines and acetylenic esters
作者:Francisco Palacios、Ana M.Ochoa de Retana、Jaione Pagalday
DOI:10.1016/s0040-4020(99)00890-x
日期:1999.12
Efficient and regioselective syntheses of 1-phenyl-5-pyrazolones substituted with a phosphoranylidene group in the 3-position and of 3-alkoxycarbonyl-5-methoxy-1-phenyl pyrazoles are described. The key step is the formation of functionalized hydrazones by [2+2] cycloaddition reaction of phosphazenes derived from hydrazines with acetylenic esters. Subsequent cyclization of these compounds with butyl