Stereoselective intermolecular addition of ketyl radicals generated from ketones by photoinduced electron transfer

Ketyl radicals were produced from ketones by photochemical electron transfer and subsequent proton transfer from tertiary amines. These radicals were stereoselectively added to (5R)-5-(−)-menthyloxy-2[5H]-furanone 1. Due to their low reactivity, the α-aminoalkyl radicals which were generated at the same time were not added to 1. The ketones were used in stoichiometric quantities.