One pot synthesis of 1-substituted tetrahydro-β-carbolines by Bischler–Napieralski cyclization

A novel and facile one-pot synthesis of 1-substituted tetrahydro-β-carbolines by cyclocondensation of ketene S,S–acetals with tryptamine in presence of InCl3 and TFA as co-catalysts by Bischler-Napieralski cyclization is described. The reaction involves formation of one C-N bond, one C-C bond and a new ring annulation over an indole moiety.