Cyanoethylation of hypocrellin A (I; R1R2 = Q), hypocrellin B derivatives (I; R1R2 = Q1, R = Ac, H) gave nitrile, acid, and amide derivatives I (R1R2 = Q2, R = H, R3 = cyano, CO2H, CONH2) and a small amount of I (R1R2 = Q2, R = Ac, R3 = CONH2). Selective photooxygenation of I (R1R2 = Q1, R = H) at l > 600 nm with methylene blue as sensitizer, followed by reduction with (PhO)3P, gave I (R1R2 = Q3), with a quantum yield of 0.24 ?0.01 for singlet O formation.

Key words: SELECTIVITY, PHOTOOXIDATION, ACRYLONITRILE, HYPOCRELLA BAMBUSAE, ETHYLATION, NITRILE, HYPOCRELLIN