title: Intramolecular Nicholas reaction: stereoselective synthesis of 5-alkynylproline derivatives.
abstract: The intramolecular Nicholas reaction of propargylic alcohols derived from N, N-acyl-diprotected omega-semialdehydes obtained from glutamic acid provided stereoselectively 5-alkynylproline derivatives. The suitable choice of the N-protecting group (tosyl or benzoyl derivative) permitted control of the stereochemistry during the ring formation. Semiempirical calculations of the species involved in the cyclization support the observed stereochemistry.
authors.affiliation: Instituto Universitario de Bio-Orgánica Antonio González Universidad de La Laguna, La Laguna, Tenerife, Spain.
authors.forename: J Nicolás
authors.initials: JN
authors.lastname: Hernández
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Ramírez
authors.forename: Matías L
authors.initials: ML
authors.lastname: Rodríguez
authors.forename: Víctor S
authors.initials: VS
authors.lastname: Martín
mesh_terms: D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D015394:Molecular Structure; D011392:Proline / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D011392:Proline