title: Lewis acid promoted intramolecular (3 + 2) 'cycloadditions' of methyleneaziridines with alkene and alkyne acceptors.
abstract: 2-Methyleneaziridines can be tethered to a variety of alkene or alkyne acceptors through the saturated carbon of the heterocyclic ring by application of a simple lithiation/alkylation sequence (8 examples, 31-59%). Treatment of the resultant alkene bearing substrates with BF(3)·OEt(2) leads to cis-octahydrocyclopenta[c]pyrroles in which up to four contiguous stereocentres are created in a diastereocontrolled manner after reductive work-up. Using an alkyne based substrate, a 2,4,5,6-tetrahydrocyclopenta[c]pyrrole is produced by rapid tautomerisation of the initially formed bisenamine. Evidence that these (3 + 2) 'cycloadditions' proceed in a stepwise manner via a 2-aminoallyl cation is presented.
authors.affiliation: Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, UK CV4 7AL.
authors.forename: Karen
authors.initials: K
authors.lastname: Griffin
authors.forename: Cyril
authors.initials: C
authors.lastname: Montagne
authors.forename: Cam Thuy
authors.initials: CT
authors.lastname: Hoang
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Clarkson
authors.forename: Michael
authors.initials: M
authors.lastname: Shipman
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D001388:Aziridines / Q000737:chemistry*; D003500:Cyclization; D058116:Lewis Acids / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D000480:Alkynes; D001388:Aziridines; D058116:Lewis Acids