title: The organocatalytic [3+2] cycloaddition of azomethine ylides and alpha,beta-unsaturated aldehydes as a convenient tool for the enantioselective synthesis of pyrrolizidines and indolizidines.
abstract: We have developed a simple and straightforward procedure for the enantioselective preparation of densely substituted bicyclic and tricyclic nitrogen heterocycles using conveniently substituted enantiopure pyrrolidines as common synthetic intermediates, which are easily accessible by our recently developed organocatalytic enantioselective [3+2] cycloaddition of alpha,beta-unsaturated aldehydes and azomethine ylides. The designed synthetic pathway makes use of a ring-closing metathesis reaction for building up the pyrrolizidine and indolizidine skeletons, while the access to the hexahydrocyclopenta[a]pyrrolizine structure has been carried out relying on a fully diastereoselective intramolecular Pauson-Khand reaction.
authors.affiliation: Departamento de Química Orgánica II, Facultad de Ciencia y Tecnología, Universidad del País Vasco/Euskal Herriko Unibertsitatea, P.O. Box 644, E-48080, Bilbao, Spain.
authors.forename: Ainara
authors.initials: A
authors.lastname: Iza
authors.forename: Luisa
authors.initials: L
authors.lastname: Carrillo
authors.forename: Jose L
authors.initials: JL
authors.lastname: Vicario
authors.forename: Dolores
authors.initials: D
authors.lastname: Badía
authors.forename: Efraim
authors.initials: E
authors.lastname: Reyes
authors.forename: Jose I
authors.initials: JI
authors.lastname: Martínez
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D001391:Azo Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D054836:Indolizidines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011763:Pyrrolizidine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013882:Thiosemicarbazones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000447:Aldehydes; D001391:Azo Compounds; D006575:Heterocyclic Compounds, 3-Ring; D054836:Indolizidines; D011763:Pyrrolizidine Alkaloids; D013882:Thiosemicarbazones; C512188:azomethine