title: Enantioselective synthesis of trans-4-methylpipecolic acid.
abstract: An asymmetric synthesis for the preparation of both enantiomers of trans-methylpipecolic acids is described. It is based on Sharpless epoxidation as a chirality source, regioselective ring opening with allylamine, and ring-closing metathesis to construct the piperidine ring. The stereogenic center at C-4 is set by stereoselective hydrogenation that is directed by the alcohol functionality of an intermediate and proceeds with good diastereomeric control (trans/cis 16/1). Crystallization of the Boc-protected amino acid afforded the target products with excellent chemical (98% de) and enantiomeric purity (99% ee).
authors.affiliation: Unitat de Recerca en Síntesi Asimètrica (URSA-PCB), Institute for Biomedical Research and Departament de Química Orgànica, Universitat de Barcelona, Parc Científic de Barcelona c/Josep Samitier, 1-5, 08028 Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alegret
authors.forename: Ferran
authors.initials: F
authors.lastname: Santacana
authors.forename: Antoni
authors.initials: A
authors.lastname: Riera
mesh_terms: D000499:Allylamine / Q000031:analogs & derivatives; D003500:Cyclization; D004852:Epoxy Compounds / Q000737:chemistry; D010875:Pipecolic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism