Summary The photochemistry of the a,/?-unsaturated y, 6-epoxy-enones 1-3 is determined by:(i) C (y)-0-scission of the epoxide (vinylogous/?-cleavage of Type A);(ii) C (y)-C (G)- cleavage of the oxirane (vinylogous P-cleavage of Type B);(iii)(E/Z)-isomerization of the enone chromophore. In contrast, 4 with tertiary C (6) shows no Type B cleavage.
