Green Synthesis of Diphenyl‐Substituted Alcohols Via Radical Coupling of Aromatic Alcohols Under Transition‐Metal‐Free Conditions.

Alcohols are common alkylating agents and starting materials alternative to harmful alkyl halides. In this study, a simple, benign and efficient pathway was developed to synthesize 1,3‐diphenylpropan‐1‐ols via the β‐alkylation of 1‐phenylethanol with benzyl alcohols. Unlike conventional borrowing hydrogen processes in which alcohols were activated by transition‐metal catalyzed dehydrogenation, in this work, t‐BuONa was suggested to be a dual‐role reagent, namely, both base and radical initiator, for the radical coupling of aromatic alcohols. The cross‐coupling reaction readily proceeded under transition metal‐free conditions and an inert atmosphere, affording 1,3‐diphenylpropan‐1‐ol with an excellent yield. A good functional group tolerance in benzyl alcohols was observed, leading to the production of various phenyl‐substituted propan‐1‐ol derivatives in moderate‐to‐good yields. The mechanistic studies proposed that the reaction could involve the formation of reactive radical anions by base‐mediated deprotonation and single electron transfer. [ABSTRACT FROM AUTHOR]