The DBU-catalyzed reaction of 1-(1-alkynyl)-2-alken-1-ones with 1,3-dicarbonyl compounds produces 4H-pyrans in moderate to excellent yield, whereas the cationic Pd(II)-catalyzed reaction affords furans regioselectively.
1-(1-炔基)-2-链烯-1-酮与 1,3-二羰基化合物的
DBU 催化反应以中等至优异的收率生成
4H-吡喃,而阳离子 Pd(II) 催化反应则产生
呋喃区域选择性。