title: 3-Formylcyclopent-3-enyl- and 3-carboxycyclopentylglycine derivatives: a new stereocontrolled approach via retro-aldol or retro-Claisen reactions.
abstract: A new synthetic approach to diastereomeric cyclopent-3-enylglycines 19/20, functionalized on the ring with a formyl group, and to cyclopentylglycine, substituted with a carboxy group (compounds 21/22), was devised by applying retro-aldol and retro-Claisen reactions, respectively, to diastereomeric 2-amino-3-ethoxycarbonyloxynorbornene-2-carboxylic acid derivatives 5, 6 and to diastereomeric 2-amino-3-oxo-norbornane-2-carboxylic acid derivatives 17, 18. The goal of controlling the cis stereochemistry of the cyclopentyl substituents was reached using compounds 17, 18. A partial control of the stereochemistry of the amino acidic carbon was achieved starting from 17 and using sodium hydrogen carbonate in acetone/DMF. From exo-17, the acid 22 was obtained as the major diastereomer.
authors.affiliation: Istituto di Chimica Organica A. Marchesini, Facoltà di Farmacia, Università di Milano, Via Venezian 21, I-20133 Milano, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Clerici
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Gelmi
authors.forename: Sara
authors.initials: S
authors.lastname: Pellegrino
authors.forename: Tullio
authors.initials: T
authors.lastname: Pilati
mesh_terms: D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D005998:Glycine / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D003517:Cyclopentanes; D005998:Glycine