Synthesis of (S)-4-(1H-indol-3-yl)-3-methyl-1-(2-methylbutyl)-1H-pyrrol-2(5H)-one Isolated from a Korean Marine Sponge of the Family Irciniidae

Abstract

An indole alkaloidal natural product was isolated from a Korean marine sponge of the family Irciniidae collected off the coast of Chuja island. The natural compound was structurally determined through the combined spectroscopic analysis to be (S)-4-(1H-indol-3-yl)-3-methyl-1-(2-methylbutyl)-1H-pyrrol-2(5H)-one. However, spectroscopic data were not decisively determine the absolute configuration of the compound. Organic synthesis was used to prepare the novel compound and compare its spectroscopic data to determine the absolute configuration of the natural product. Retrosynthesis of the target compound was carried out. The initial mode of approach was to synthesize the lactam and indole moiety separately and conjugate them subsequently. Several schemes were devised and performed. However, this approach proved to be unsuccessful, particularly with the conjugation of the two moieties. An alternative approach was to cyclize the lactam ring moiety onto the indole group. Several schemes were devised and attempted with this, but none have been able to produce the final product. Future studies based on different approaches will be required for the successful synthesis of the natural product.