title: Asymmetric aza-[3+3] annulation in the synthesis of indolizidines: an unexpected reversal of regiochemistry.
abstract: An enantioselective and diastereoselective aza-[3+3] annulation of pyrrolidine-based exo-cyclic vinylogous amides and urethanes with chiral vinyl iminium salts is described. This asymmetric annulation manifold is possible because of an unexpected regiochemical reversal whereby head-to-tail annulations dominated over the predicted head-to-head. It should find prevalent synthetic applications in the enantioselective synthesis of indolizidines.
authors.affiliation: Division of Pharmaceutical Sciences and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53705, USA.
authors.forename: Grant S
authors.initials: GS
authors.lastname: Buchanan
authors.forename: Huifang
authors.initials: H
authors.lastname: Dai
authors.forename: Richard P
authors.initials: RP
authors.lastname: Hsung
authors.forename: Aleksey I
authors.initials: AI
authors.lastname: Gerasyuto
authors.forename: Casi M
authors.initials: CM
authors.lastname: Scheinebeck
mesh_terms: D001372:Aza Compounds / Q000737:chemistry*; D054836:Indolizidines / Q000138:chemical synthesis*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001372:Aza Compounds; D054836:Indolizidines