finding is surprising since dienes, in general, are better known as quenchers of enone triplets rather than as photochemical reactants. Both the high substrate concentrations, which can be employed in these cycloadditions, and the remarkable regio and stereoselectivity of the processes qualify them as valuable for syntheses. In a first application, the photoproducts 1a, b were transformed in three steps
2-(三甲基甲
硅烷氧基)-
1,3-丁二烯与许多2-环烯酮的[2 + 2]光环加成被证明是相当普遍的反应,导致良好的环加合物收率(表)。这一发现是令人惊讶的,因为通常将二烯称为烯酮三联体的猝灭剂而不是光
化学反应剂。可以在这些环加成反应中使用的高底物浓度,以及过程的显着区域和立体选择性都使它们对合成有价值。在第一个应用中,将光产物1a,b分三步转化为
戊烯戊内酯-G和-H抗生素的可行前体4。