The synthesis of ascididemin

Article abstract of DOI:10.1016/S0040-4020(01)88497-0

A short synthsis of the pentacyclic marine alkaloid ascididemin 1 (four steps, 21% yield) from 1,10-phenanthroline 16 is described. The key step, photocyclisation of the quinoneimine 14 in sulphuric acid, is the first such aza stilbene photocyclisation of a quinoneimine. Intermediate 14 is prepared in a single, but low yielding, step from the quinone 4 in an aza Wadsworth-Emmons reaction, or in much better yield from the epoxide 17 by treatment with 2- iodoaniline and triethylaluminium, followed by oxidation with barium manganate.