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
描述了在3-位被磷亚烷基取代的1-苯基-5-吡唑啉酮和3-烷氧基羰基-5-甲氧基-1-苯基吡唑的高效和区域选择性合成。关键步骤是通过衍生自肼的磷腈与炔属酯的[2 + 2]环加成反应形成官能化的。随后用丁基锂将这些化合物环化,得到取代的5-吡唑啉酮,同时将它们与乙腈一起加热可形成区域选择性的3-烷氧基羰基-5-甲氧基-1-苯基吡唑。