HIGHLY STEREOSELECTIVE FORMATION OF 1,3-DIOXOLANES BY PHOTOCATALYTIC RING OPENING REACRIONS OF alpha-EPOXYKETONES IN ACETONE SOLUTION USING 1-BENZYL-2,4,6-TRIPHENYLPYRIDINIUM TETRAFLUOROBORATE (NBTPT)

摘要

Highly stereoselective formation of 1,3-dioxolanes has been observed on photoinduced electron transfer ring opening of alpha-epoxyketones by l-benzyl-2,4,6-triphenylpyridinium tetrafluoroborate (NBTPT) in acetone solution.The presence of various substituents on the donor molecule has not affected the rate of the ring opening and also stereoselectivity of the reaction too much.Stepwise addition of the photocatalyst leads to decreasing of irradiation time and increasing of the yield of products.Photoinduced electron transfer deoxygenation and isomerization of some alpha-epoxyketones has also been observed.Cyclic voltammetric study of the photocatalyst shows a greater tendency of NBTPT for accepting an electron in the excited state.