Photoinduced ring opening of a-epoxyketones 1a-f has been investigated by triphenylpyrilium tetrafluoroborate (TPT) as photocatalyst in methanol solution. The effect of substituent on the rate of oxiran ring opening and on the stereochemistry of the reaction has been studied. The electron donating groups have shown to increase the rate of ring opening, however, the stereoselectivity of the reaction is diminished due to the type and the stability of the reaction intermediates.
