An efficient and general strategy for the synthesis of 4-phosphorylated pyrazoles from β-hydrazono phosphine oxides
作者:Francisco Palacios、Domitila Aparicio、Jesús M. de los Santos
DOI:10.1016/s0040-4020(96)00073-7
日期:1996.3
A simple and efficient synthesis of aminopyrazoles substituted with a phosphino oxide and sulphide groups in the 4-position 1 is described. The key step is a regioselective addition of lithiated β-hydrazonophosphine oxides 2 to isocyamates and isothiocyanates to give functionalized amides 3 and 7. Subsequent cyclization of 3 with phosphorus oxychloride in the presence of triethylamine afforded pyrazoles