Base-promoted, CBr4-mediated tandem bromination/intramolecular Friedel-Crafts alkylation of N-aryl enamines: a facile access to 1H- and 3H-indoles

Org Biomol Chem. 2021 Jun 28;19(24):5377-5382. doi: 10.1039/d1ob00731a. Epub 2021 May 28.

Abstract

Described here is a general and highly efficient method for the synthesis of 1H- and 3H-indoles. In the presence of CBr4 and a suitable base, the cyclization of N-aryl enamines proceeds with high efficiency. Unlike previous intramolecular cross dehydrogenative coupling (CDC) of the same substrates, this process does not require the use of either a transition metal or a stoichiometric amount of oxidant. This method also features operational simplicity, easy scalability and good substrate tolerability. Control experiments indicate the reactions may proceed in a tandem sequence of bromination and intramolecular Friedel-Crafts alkylation in a simple one-pot procedure.

Publication types

  • Research Support, Non-U.S. Gov't