ChemInform Abstract: Generation of α‐Acylcarbenium Ions: A Novel Uncatalyzed C‐C Bond Formation at Room Temperature.

Abstract

ChemInform Abstract A wide range of reactions of desyl chlorides such as (II) with different phenols such as (I), (V), or (VIII) is studied. The results indicate the generation of α-acylcarbenium ions such as An-+CH-CO-An in a non-polar medium (and a novel uncatalyzed -C bond formation with phenols) if the parent desyl chlorides are substituted by oxygen para to the CH-Cl group. If the phenols present are para-alkylated by the carbenium ion then phenols such as (VI) are obtained; if alkylation occurs ortho to the phenolic OH then enzofurans such as (III), (VII), and (IX) are produced, providing a new one-step benzofuran synthesis. In polar media (K2CO3, e.g.), normal substitution (e.g., to give (IV)) competes with C-C bond formation (to yield (IIIa)) or dominates.