NNN Palladium(II)-Pincer Complex in a Borrowing Hydrogen Process: Alkylation of Indoles

Abstract

Recently, an azine NNN-Pd(II) non-palindromic pincer complex was generated, and its application in acceptorless dehydrogenative coupling (ADC) was explored. This article establishes the application of the same pincer complex in the borrowing hydrogen process (BHP). Herein, we report the selective synthesis of C-3 alkylated indoles (CAIs). Remarkably, this catalyst enables bis(indolyl)methanes (BIMs) synthesis by tuning the reaction conditions from the same substrates. The control experiments and quantum chemical analysis suggest that C-3 functionalization of indole involves a “Borrowing Hydrogen Process.’’ The formation of BIMs is an additional advantage.