A catalytic versus stoichiometric photoinduced electron transfer promoted selective C16C21 bond cleavage of catharanthine

A clean and efficient access to the cleavamine skeleton is described through the selective oxidative C16C21 bond cleavage of catharanthine. The best result is obtained by the use of catalytic quantities of β-lapachone as photosensitizer, which permits the successful control of competition between the back electron transfer, the deprotonation and the fragmentation pathway.