Enantioselective Synthesis and Antimicrobial Activities of Tetrahydro-Β-Carboline Diketopiperazines

A series of single isomers tetrahydro- β -carboline diketopiperazines were stereoselectively synthesized starting from l -tryptophan methyl ester hydrochloride and six aldehydes through a four-step reaction including Pictet-Spengler reaction, crystallization-induced asymmetric transformations (CIAT), Schotten-Baumann reaction, and intramolecular ester amidation. The chemical structures were characterized by nuclear magnetic resonance (NMR) and elemental analysis, among which two compounds were determined by x-ray single crystal diffraction. Moreover, antimicrobial activities of all the compounds were also tested. Chirality 25:656–662, 2013 . © 2013 Wiley Periodicals, Inc.