Enantioselective BINOL-Phosphoric Acid Catalyzed Pictet−Spengler Reactions of N-Benzyltryptamine

• Published in: Journal of organic chemistry 2008-08, Vol.73 (16), p.6405-6408
• Main Authors: Sewgobind, Nishant V, Wanner, Martin J, Ingemann, Steen, de Gelder, René, van Maarseveen, Jan H, Hiemstra, Henk
• Format: Article
• Language: English
• Subjects: Aldehydes - chemistry; Benzyl Compounds - chemistry; Carbolines - chemical synthesis; Carbolines - chemistry; Catalysis; Catalysts: preparations and properties; Chemistry; Condensed benzenic and aromatic compounds; Exact sciences and technology; General and physical chemistry; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Naphthols - chemistry; Organic chemistry; Oxidation-Reduction; Phosphoric Acids - chemistry; Preparations and properties; Stereoisomerism; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Tryptamines - chemistry
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo8010478

Optically active tetrahydro-β-carbolines were synthesized via an (R)-BINOL-phosphoric acid-catalyzed asymmetric Pictet−Spengler reaction of N-benzyltryptamine with a series of aromatic and aliphatic aldehydes. The tetrahydro-β-carbolines were obtained in yields ranging from 77% to 97% and with ee values up to 87%. The triphenylsilyl-substituted BINOL-phosphoric acid proved to be the catalyst of choice for the reaction with aromatic aldehydes. For the aliphatic aldehydes, 3,5-bistrifluoromethylphenyl-substituted BINOL-phosphoric acid was identified as the best catalyst.