Studies on Total Synthesis of Ageliferins, Pyrrole-Imidazole Marine Alkaroids

Abstract

Ageliferins 1—3 were isolated from a Caribbean marine sponge, Agelas coniferin, by Rinehart et al. in 1989, and Kobayashi reported that these alkaloids had several interesting biological properties such as actomyosin ATPase and antiviral activities. 1-Benzyl-5-[(2-methoxycarbonyl)ethenyl]-2-phenylsulfanyl-1H-imidazole (10) was prepared in 46 % yield by regioselective N-alkylation of 4-formyl-2-phenylsulfanyl-1H-imidazole (7e) with benzyl bromide in the presence of ZnCl₂ and DBU. Diels–Alder dimerization at 140°C of 10 stereoselectively gave the dimer (8e). The dimer (8e) reduced by LiAlH₄ followed by NaBH₄/NiCl₂ to the diol (13) (R = H), which was an important intermediate for ageliferins 1—3. Herein, we are going to report the above-mentioned chemistry and recent progress of the investigation.