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.
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]
Silveira
Claudio C
CC
Departamento de Química, Universidade Federal de Santa Maria, 97105.900, Santa Maria, RS, Brazil. silveira@quimica.ufsm.br
Felix
Luciana A
LA
Braga
Antonio L
AL
Kaufman
Teodoro S
TS