Organophosphorus-catalyzed diaza-Wittig reaction: application to the synthesis of pyridazines.

The elaboration of the first organophosphorus-catalyzed diaza-Wittig reaction is reported. This catalytic reaction is applied to the synthesis of substituted pyridazine and phthalazine derivatives bearing electron-withdrawing groups with good to excellent yields from substrates containing a diazo functionality as the starting material and a phospholene oxide as the catalyst.