Synthesis of granulatimide positional analogues.

The Stille coupling reaction of the stannylindole 13 with the 5-iodoimidazole derivative 14 (or 27) in the presence of PdCl(2)(PPh(3))(2) gave the corresponding indole-imidazole coupling product 15 (or 28), thereby affording a synthetic approach to 10-methylgranulatimide (7), 15-methylgranulatimide (11), and 10, 15-dimethylgranulatimide (12), as well as 10-methylisogranulatimide B (5).

New synthetic route to granulatimide and its structural analogues.

The Stille coupling reaction of stannylindole 12 with 4-iodoimidazole 13 (or 24) in the presence of PdCl(2)(PPh(3))(2) gave the corresponding indole-imidazole coupling product 14 (or 25), thereby affording a new synthetic approach to the alkaloid granulatimide (7), isolated from the Brazilian ascidian Didemnum granulatum, as well as its structural analogues, 10-methylgranulatimide (23), 17-methylgranulatimide (30), 10,17-dimethylgranulatimide (31).