title: Highly selective copper-catalyzed asymmetric [3+2] cycloaddition of azomethine ylides with acyclic 1,3-dienes.
abstract: The first examples of the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides with acyclic activated 1,3-dienes (and 1,3-enynes) are described. Under copper catalysis, a selective cycloaddition at the terminal γ,δ-C=C bond is observed. In addition, depending on the ligand used, either the exo or the endo adduct can be obtained with high selectivity. Under appropriate reaction conditions, the acyclic 1,6-addition product is detected, suggesting a stepwise mechanism. The resulting C4-alkenyl-substituted pyrrolidines are suitable substrates for further access to polycyclic systems, as highlighted by the preparation of hexahydrochromeno[4,3-b]pyrrole and the tetracyclic core of the alkaloid gracilamine.
authors: Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid (Spain), Fax: (+34) 914973966.
authors: María
authors: M
authors: González-Esguevillas
authors: Ana
authors: A
authors: Pascual-Escudero
authors: Javier
authors: J
authors: Adrio
authors: Juan C
authors: JC
authors: Carretero
mesh_terms: D000480:Alkynes / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D061565:Cycloaddition Reaction; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D000480:Alkynes; D001391:Azo Compounds; D013882:Thiosemicarbazones; C512188:azomethine; D003300:Copper
keywords: asymmetric catalysis; azomethine ylides; copper; cycloaddition; dienes