Collective Synthesis and Biological Evaluation of Tryptophan-Based Dimeric Diketopiperazine Alkaloids.

A concise two one-pot synthesis of WIN 64821, eurocristatine, 15,15'-bis-epi-eurocristatine, ditryptophenaline, ditryptoleucine A, WIN 64745, cristatumin C, asperdimin, naseseazine A, and naseseazine B is detailed, based on a unique bioinspired dimerization reaction of tryptophan derivatives in aqueous acidic solution and a one-pot procedure for the construction of diketopiperazine rings. Total yields of these alkaloid syntheses were from 10 up to 27 %. In addition, 1'-(2-phenylethylene)-ditryptophenaline was synthesized by using three one-pot operations.