An Expedient Protocol to the Synthesis of Benzo(b)furans by Palladium Induced Heterocyclization of Corresponding 2‐Allylphenols Containing Electron Rich and Electron Capturing Substituents in the Arene Ring

Abstract

A facile and rapid accessibility to the libraries containing several mono, and disubstituted benzo(b)furan derivatives substituted with a variety of electron rich and electron capturing groups on 2, 4, 5, 6, and 7 positions of its nucleus has been explored using the PdCl 2 (CH 3 CN) 2 catalyzed heterocyclization of the corresponding 2-allylphenols to afford 2(a-m) in good yield and high purity.

The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence

“…[15] These include the formation of the furan ring from ortho-substituted phenol derivatives e.g. by Pd(II)-catalyzed cyclization of o-alkenyl or o-alkynyl phenols [ 16 ] , acid catalyzed dehydration of o-hydroxybenzyl ketones [17] or via Pd(II)-mediated Sonogashira cross-coupling of o-halophenols with alkynes. [ 18 ] However, while considering the possible reaction pathways for the benzofuran ring formation within the resorcinarene skeleton that lacks an electron deficient -carbon atom at the ortho substituent (Scheme 1), the only conceivable alternative seems to be a radical reaction mechanism initiated by DMF radicals.…”