3-(Tetrahydropyridinyl)indoles

Article abstract of DOI:10.1016/0040-4020(96)00553-4

Substituted indoles have been condensed with N-benzyl-4-piperidone to give 3-(1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indoles. Under basic conditions, 5-, 6-, and 7- (but not 4-) substituted indoles give reasonable yields of the product. For condensation with 4-substituted indoles, acidic conditions and the presence of at least a 3-fold excess of N-benzyl-4-piperidone are beneficial. Under basic conditions, the condensation of indoles with N-substituted-3-piperidones is highly regioselective with the regioselectivity depending on the nature of the N-substituent. 4-Substituted indoles do not react with N-substituted-3-piperidones under basic conditions but give a single product under acidic conditions.