Regiospecific [2+2] cycloadditions of electron-poor acetylenes to (Z)-2-acylamino-3-dimethylaminopropenoates: synthesis of highly functionalised buta-1,3-dienes

Microwave-assisted [2+2] cycloaddition reactions of 2-amino-3-dimethylaminopropenoates with acetylenecarboxylates furnished highly functionalised 1-amino-4-(dimethylamino)buta-1,3-dienes in 40–94% yields. All reactions were observed to consistently produce single geometrical isomers, and in cases where non-symmetrical acetylenes were employed the reactions proceeded in a regiospecific manner.