Tsuji-Wacker-Type Oxidation beyond Methyl Ketones: Reacting Unprotected Carbohydrate-Based Terminal Olefins through the 'Uemura System' to Hemiketals and alpha,beta-Unsaturated Diketones

摘要

Aerobic Pd(AcO)(2)/pyridine-catalyzed oxidation of unprotected carbohydrate-based terminal alkenes was studied. In accordance with previous reports, the initial reaction step gave methyl ketones. However, our substrates partially gave subsequent alpha,beta-water elimination and alcohol oxidation to alpha,beta-unsaturated 2,5-diketones. Upon increasing the pressure of O-2, the reaction was shifted toward formation of alpha,beta-epoxy-2-ketones. The reactions were stereoselective and gave up to quantitative conversions. However, isolated yields were substantially lower because of the complexity of the product mixtures.