Conjugated azoalkenes. Part XI. Direct synthesis of substituted pyrazoles and 4-triphenylphosphoranylidene-4,5-dihydropyrazol-5-ones by heterocyclization of some zwitterionic 1,4-adducts between conjugated azoalkenes and triphenylphosphine
作者:Orazio A. Attanasi、Paolino Filippone、Amedeo Mei
DOI:10.1016/s0040-4020(01)88729-9
日期:1992.2
The simple and direct synthesis in good yields of substituted pyrazoles and 4-triphenylphosphoranylidene-4,5-dihydropyrazol-5-ones is reported. These products have been prepared by heterocyclization under different reaction conditions of some 1,5-zwitterionic species obtained from the 1,4-conjugate addition of triphenylphosphine to the azo-ene system of conjugated azoalkenes.