FeCl₃‐Mediated Friedel‐Crafts Alkylation and Oxidative Annulations: Facile Synthesis of Benzofurans

Abstract

An efficient method for the facile synthesis of benzofurans through FeCl3‐mediated intermolecular tandem reaction of anisole with glyoxal monohydrates was reported. This process provided the privileged structures of benzofurans in moderate to good yields under mild conditions. This reaction has many advantages, such as readily available starting materials, high atom economy and good functional group tolerance. This is firstly reported that FeCl3, acting as both a Lewis acid and an oxidant, was used for the synthesis of benzofuran.

Aryl glyoxal: a prime synthetic equivalent for multicomponent reactions in the designing of oxygen heterocycles

“…This reaction offers a lot of benefits, like readily available starting materials, high atom economy, and strong functional group tolerance (Scheme 31). 62 The mechanistic steps for the annulation reaction include the Friedel–Craft alkylation of 1 with anisole 61 forming the intermediate la , which in turn is oxidized by FeCl 3 to generate the second radical cation intermediate lb . FeCl 3 is then reduced second time to further oxidize lc with a subsequent intramolecular cyclization followed by dehydration to yield the annulated benzofuran 63 (Scheme 32).…”