title: Photoaddition reactions of 1,2-diketones with silyl ketene acetals. formation of beta-hydroxy-gamma-ketoesters.
abstract: 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 beta-hydroxy-gamma-ketoesters, generated by SET-promoted Claisen-type condensation. These competitive pathways leading from the excited states of the 1,2-diketones to these products are influenced by solvent polarity and the nature of the silyl ketene acetal and 1,2-diketone. The Claisen-type condensation process, following an SET desilylation pathway and predominating when the photoreactions are carried out in the polar solvent acetonitrile, represents an efficient method to prepare a variety of diversely substituted beta-hydoxy-gamma-ketoesters.
authors.affiliation: Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, Korea.
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Cho
authors.forename: Hyang-Yeol
authors.initials: HY
authors.lastname: Lee
authors.forename: Sun Wha
authors.initials: SW
authors.lastname: Oh
authors.forename: Jung Hei
authors.initials: JH
authors.lastname: Choi
authors.forename: Hea Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Mariano
authors.forename: Ung Chan
authors.initials: UC
authors.lastname: Yoon