Syntheses of polybrominated indoles from the red alga Laurencia brongniartii and the brittle star Ophiocoma erinaceus.

The red alga Laurencia brongniartii and brittle star Ophiocoma erinaceus metabolites 2,3,6-tribromo-1-methylindole (1) and 2,3,5,6-tetrabromo-1-methylindole (2) are easily synthesized selectively from 2,3-dibromo-1-methylindole (5), which in turn is prepared from indole (3) in one continuous sequence in 92% yield. Moreover, 2 can be made from both 1 and 5 in 67% and 65% yields, respectively.