The results of a study of the cycloaddition reaction of bromonitrilimine with (Z)-4-(arylmethylidene)isoxazol-5-ones and pyrazol-5-ones are reported. Spectroscopic and X-ray crystallographic data are presented to support structural assignments of the reaction products.
Synthesis of 4-Arylidenepyrazolones by a Gold-Catalyzed Cyclization/Arylidene Group Transfer Cascade of <i>N</i>-Propioloyl Hydrazones
An efficient gold-catalyzedcyclization/arylidene group transfer cascade reaction of N-propioloyl hydrazones has been developed. This method provides a novel approach for the synthesis of various functionalized 4-arylidenepyrazolones.
2-arylbenzimidazolines (8), generated in situ from o-phenylenediamine (7) and the appropriate arylaldehydes, by reaction with 4-arylmethylenepyrazol-5-ones (1) or isoxazol-5-ones (2) produce the 4-arylmethylderivatives (3) or (4) and the C,C- (5) or the C,N-linkeddimers. The reaction was rationalised on the basis of the role of 2-arylbenzimidazoline as a reducing agent and proceeds by a non-chain