3-(TETRAHYDROPYRIDINYL)INDOLES

Substituted indoles have been condensed with N-benzyl-4-piperidone to give benzyl-1,2,3,6-tetrahydropyridin-4-yl)-1H-indoles. Under basic co nditions, 5-, 6-, and 7- (but not 4-) substituted indoles give reasona ble yields of the product For condensation with 4-substituted indoles, acidic conditions and the presence of at least a 3-fold excess of N-b enzyl-4-piperidone are beneficial. Under basic conditions, the condens ation of indoles with N-substituted-3-piperidones is highly regioselec tive with the regioselectivity depending on the nature of the N-substi tuent. 4-Substituted indoles do not react with N-substituted-3-piperid ones under basic conditions but give a single product under acidic con ditions. Copyright (C) 1996 Elsevier Science Ltd