Chemical transformation of protoberberines. Part 10. A novel synthesis of sanguilutine and dihydrosanguilutine, fully aromatised 2,3,7,8,10-pentaoxygenated benzo[c]phenanthridine alkaloids
Abstract
2,3,7,8,10-Pentaoxygenated benzo[c]phenanthridine alkaloids, sanguilutine (1), and dihydrosanguilutine (2), were efficiently synthesised from the corresponding 2,3,9,10,12-pentamethoxyprotoberberine (8) through a regioselective C(6)–N bond cleavage, followed by recombination between the original C(6) and C(13) positions of compound (8) according to a biomimetic route.