title: 1-substituted beta-carbolines by a Pictet-Spengler cyclization with thioortho esters and carbon-carbon bond formation via N-sulfonyl iminium ions generated from N,S-sulfonyl acetals.
abstract: The reaction of N-tosyltryptamines with thioortho esters, leading to 1-thiosubstituted tetrahydro-beta-carbolines under modified Pictet-Spengler conditions, is described. The 1-heterosubstituted beta-carbolines furnished 1-substituted beta-carbolines upon reaction with Grignard reagents and silyl derivatives under Lewis acid promotion. [reaction: see text]
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105.900, Santa Maria, RS, Brazil. silveira@quimica.ufsm.br
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Silveira
authors.forename: Luciana A
authors.initials: LA
authors.lastname: Felix
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Braga
authors.forename: Teodoro S
authors.initials: TS
authors.lastname: Kaufman