title: Syntheses of Strychnan- and Aspidospermatan-Type Alkaloids. 9.(1) The Enantioselective Generation of Tetracyclic ABCE Intermediates by a Tandem Condensation, [3,3]-Sigmatropic Rearrangement, and Cyclization Sequence.
abstract: Reactions of substituted acroleins with the tryptophan-derived benzyl 2-(benzylamino)-3-[3-[2-[(methoxycarbonyl)methyl]indolyl]]propionate gave tetracyclic hexahydro-1H-pyrrolo[2,3-d] intermediates with stereoselective placement of substituents for cyclization to pentacyclic Strychnos alkaloids. The benzyl ester moiety was readily removed by formation of a corresponding nitrile and reduction, thus providing enantioselective syntheses of the tetracyclic compounds.
authors.affiliation: Department of Chemistry, University of Vermont, Burlington, Vermont 05405.
authors.forename: Martin E.
authors.initials: ME
authors.lastname: Kuehne
authors.forename: Feng
authors.initials: F
authors.lastname: Xu