title: A catalytic diastereoselective formal [5+2] cycloaddition approach to azepino[1,2-a]indoles: putative donor-acceptor cyclobutanes as reactive intermediates.
abstract: A catalytic formal [5+2] cycloaddition approach to the diastereoselective synthesis of azepino[1,2-a]indoles is reported. The reaction presumably proceeds through a Lewis acid catalyzed formal [2+2] cycloaddition of an alkene with an N-indolyl alkylidene β-amide ester to form a donor-acceptor cyclobutane intermediate, which subsequently undergoes an intramolecular ring-opening cyclization. Azepine products are formed in up to 92% yield with high degrees of diastereoselectivity (up to 34:1 d.r.).
authors.affiliation: School of Chemistry and Biochemistry, Georgia Institute of Technology (USA).
authors.forename: Raynold
authors.initials: R
authors.lastname: Shenje
authors.forename: M Cynthia
authors.initials: MC
authors.lastname: Martin
authors.forename: Stefan
authors.initials: S
authors.lastname: France
mesh_terms: D001381:Azepines / Q000737:chemistry*; D002384:Catalysis; D061565:Cycloaddition Reaction; D003503:Cyclobutanes / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001381:Azepines; D003503:Cyclobutanes; D007211:Indoles
keywords: azepines; cycloaddition; cyclobutanes; fused-ring systems; synthetic methods