yields. Cyclization occurred between the excited carbonyl group and the carbon a to the sulfur on the remote side. The more methylenes placed between the carbonyl group and the sulfide, the lower the yield of 3 while intermolecular hydrogen abstraction induced reductive dimerization and intramolecular Norrish Type II photolysis become competitive. The remote cyclization can be rationalized by a photoinduced
乙
硫基烷基
苯乙醛酸酯(2)进行区域选择性光环化,以高收率产生多达13元的环
噻唑(3)。在激发的羰基和碳a到远端的
硫之间发生环化。在羰基和
硫化物之间放置的亚甲基越多,3的收率越低分子间氢提取引起的还原二聚作用和分子内的Norrish II型光解作用具有竞争性。可以通过从
硫原子到激发的羰基的光诱导电子转移,然后进行质子转移和随后的双自由基环化,使远程环化合理化。随着连接电子给体和受体的链变得更长和更柔韧,电子传输的速率常数增加。