Room Temperature Transfer Hydrogenation of Aldehydes Using Methanol Catalyzed by Iridium(III) Pyridylidene-Indole Complex

An air- and moisture-stable, electron-rich (L)Ir(III)Cp* catalyst, incorporating ligand (L) with the high σ-donor properties of pyridylidene and indole moieties, efficiently transfers hydrogen from methanol to aldehydes, converting them to alcohols with high selectivity and turnover frequencies at low temperatures (10–25 °C). Tolerant to a wide range of functional groups across 49 substrates, the catalyst is reusable, scalable to gram-scale production, and reduces energy consumption, highlighting its potential for advancing catalytic transfer hydrogenation.