Tandem site-selective bromination and highly regioselective Heck reaction of N-allyl enaminones: chemodivergent synthesis of polysubstituted pyrroles and pyridines

Abstract

The Heck reaction is an efficient strategy for constructing C–C bonds, but a one-pot bromination followed by a Heck reaction of N-allyl enaminones has remained completely unexplored. In this paper, we present the first example of a cascade transient halogenation and Heck reaction of N-allyl enaminones for the direct formation of pyrrole and pyridine heterocycles by simply varying the substituents of N-allyl enaminones. This method not only overcomes the limitations of previously known Heck reactions, such as the requirement for the pre-installation of a halogen atom at a desired position, but also addresses the issue of regioselectivity in Heck reactions with N-allyl enaminones as substrates. The ready availability of materials, inexpensive reagents, and excellent functional group compatibility make this method a valuable synthetic tool for constructing polysubstituted pyrroles and pyridine scaffolds, thereby enhancing the potential of this protocol for applications in the pharmaceutical industry.