Photocatalytic ring opening of α-epoxyketones in cyclopentanone

摘要

Electron transfer-induced ring opening of α-epoxyketones by 2,4,6-triphenylpyrylium tetrafluoroborate (TPT) in cyclopentanone resulted in the diastereoselective formation of 2,5-dioxaspiro[4,4]- nonanes through Cα-O bond cleavage and following nucleophilic attack of cyclopentanone to radical cation intermediates. The readiness for ring opening is influenced by the nature and the location of the additional substituent on the α-epoxyketones.