Fischer indole synthesis of the indoloquinoline alkaloid: cryptosanguinolentine

A new synthesis of an indoloquinoline alkaloid, isolated from Cryptolepis sanguinolenta, is described using a Fischer indole cyclization. 4-Hydroxy-1-methyl-1H-quinolin-2-one reacted directly with phenylhydrazine hydrochloride to give the indoloquinoline, which was reacted with POCl3 and then the resultant halide hydrogenolysed to give cryptosanguinolentine.