Ultrasound assisted Mizoroki–Heck coupling/C–H amination in a single pot: Direct synthesis of indole derivatives

Abstract

A one-pot protocol based on coupling-cyclization strategy has been developed for the construction of indole ring leading to 2-substituted indole derivatives. The methodology involved ultrasound assisted Mizoroki–Heck coupling in the initial step followed by C–H amination in the second step in the same pot. The C–C bond forming reaction in the first step was catalyzed by Pd/C-PPh3 catalyst system whereas the C–N bond formation in the second step was mediated by DDQ. A number of indoles were prepared in good to acceptable yield by treating 2-iodosulfanilides with various alkenes under this condition. The rapid conversions along with the use of inexpensive catalyst as well as oxidant are key features of this method. Keywords: Indole, Mizoroki–Heck coupling, Pd/C, C–H amination, Ultrasound