Irradiation of 2-styryl-4H-chromen-4-ones (1) with a high pressure Hg lamp at room temperature under air gave benzo [α] xanthones (2). The cyclization of methoxy-substituted styrylchromones occurred at the para position relative to the OMe group on the styryl ring, whereas 2-[β-(2-naphthyl) vinyl] chromone (3) cyclized at the α-position of the naphthalene ring.
在室温空气中用高压
汞灯辐照 2-
苯乙烯基-4H-苯并
吡喃-4-酮 (1),可得到苯并 [α]
黄酮 (2)。甲氧基取代的
苯乙烯基
色酮的环化发生在
苯乙烯基环上相对于 OMe 基团的对位,而 2-[β-(2-
萘基)
乙烯基]
色酮(3)则在
萘环的 α 位发生环化。