Photoaddition Reactions of 1,2-Diketones with Silyl Ketene Acetals. Formation of β-Hydroxy-γ-ketoesters
作者:Dae Won Cho、Hyang-Yeol Lee、Sun Wha Oh、Jung Hei Choi、Hea Jung Park、Patrick S. Mariano、Ung Chan Yoon
DOI:10.1021/jo800473x
日期:2008.6.1
Photochemical reactions taking place between 1,2-diketones and silyl ketene acetals and their excited state reaction mechanisms have been explored. Irradiation of benzene, acetone, or acetonitrile solutions containing 1,2-diketones and silyl ketene acetals is observed to promote formation of 1,4-dioxenes, resulting from [4 + 2]-cycloaddition, oxetanes, arising by Paterno−Buchi processes, and β-hydroxy-γ-ketoesters
研究了1,2-二酮与甲硅烷基烯酮缩醛之间的光化学反应及其激发态反应机理。观察到辐照含有1,2-二酮和甲硅烷基乙烯酮缩醛的苯,丙酮或乙腈溶液可促进1,4-二恶烯的形成,这是由[4 + 2]-环加成,氧杂环丁烷引起的,是由Paterno-Buchi过程产生的,和SET促进的Claisen型缩合反应生成的β-羟基-γ-酮酸酯。从1,2-二酮的激发态到这些产物的这些竞争途径受溶剂极性以及甲硅烷基烯酮缩醛和1,2-二酮性质的影响。克莱森(Claisen)型缩合过程遵循SET的去甲硅烷基化途径,并且在极性溶剂乙腈中进行光反应时占主导地位,