γ‐Alumina‐Supported Silver Cluster for <i>N</i>‐Benzylation of Anilines with Alcohols

Abstract

Abstract An alumina‐supported silver cluster with a Lewis acidic cocatalyst (polyvalent metal salts, such as FeCl 3 ⋅6 H 2 O) acts as a heterogeneous and recyclable catalyst for the direct N ‐alkylation of anilines with benzyl alcohols, which is driven by the borrowing hydrogen mechanism. Systematic studies on the effects of metal (Pt, Pd, Au, and Ag), silver particle size, support oxides (CeO 2 , ZrO 2 , Al 2 O 3 , SiO 2 ), and Lewis acidic additives show four important factors required to achieve selective N ‐alkylation of anilines: 1) metal with a weak metal–hydrogen bond energy (i.e., Ag), 2) smaller size of the silver cluster, 3) the support having both acidic and basic sites (i.e., Al 2 O 3 ), and 4) additives with high Lewis acidity (i.e., Fe III salt). Fundamental information will be useful for the rational design of platinum‐group metal‐free heterogeneous catalysts for environmentally benign CN bond forming reactions.