Diaminophosphonium diazaylides 2 react under mild conditions with diphenylacetyl chloride, to afford diphenyl-N-(substituted) ketenimines 4 or, depending on the case, their transformation products: either the tautomer 8, or the dimer 9. The general reaction seems to proceed firstly via an elimination step on the acid chloride followed then by an aza-Wittig reaction between the resulting ketene 7 and the diaminophosphonium monoazaylide 6.
