N-Alkylation of Aqueous Ammonia with Alcohols Leading to Primary Amines Catalyzed by Water-Soluble N-Heterocyclic Carbene Complexes of Iridium

Abstract A new catalytic system for the N‐monoalkylation of aqueous ammonia with a variety of alcohols was developed. Water‐soluble dicationic complexes of iridium bearing N‐heterocyclic carbene and diammine ligands exhibited high catalytic activity for this type of reaction on the basis of hydrogen‐transfer processes without generating harmful or wasteful byproducts. Various primary amines were efficiently synthesized by using safe, inexpensive, and easily handled aqueous ammonia as a nitrogen source. For example, the reaction of 1‐(4‐methylphenyl)ethanol with aqueous ammonia in the presence of a water‐soluble N‐heterocyclic carbene complex of iridium at 150 °C for 40 h gave 1‐(4‐methylphenyl)ethylamine in 83 % yield.