Acylation of alkylidenepyrrolidines with heterocumulenes-a reinvestigation

The reactions of alkylidenepyrrolidine esters with isocyanates generally favour C-acylation, except in the case of benzyl isocyanate. Reactions with alkyl isocyanates are slow, and require forcing conditions. Reactions with isothiocyanates give exclusively the C-acylated products.

The title reactions give predominantly the C-acyl products rather than the previously-reported N-acyl products.