Beyond the aza-Morita-Baylis-Hillman reaction: Lewis base-catalyzed reactions of N-Boc-imines with ethyl 2,3-butadienoate.

Lewis base catalyzed reactions of N-Boc-imines and ethyl 2,3-butadienoate were investigated systematically. The normal aza-Morita-Bylis-Hillman products were obtained in good to excellent yields catalyzed by DABCO. When PPh(3) was used as the catalyst, novel rearrangement product (E)-ethyl 2-((Z)-(tert-butoxycarbonylimino)(aryl)methyl)but-2-enoates could be formed in moderate yields.