Room temperature transfer hydrogenation of aldehydes using methanol catalyzed by the iridium(III) pyridylidene-indole complex.

An air- and moisture-stable, electron-rich (L)Ir(III)Cp* catalyst, incorporating a ligand (L) with the high σ-donor properties of pyridylidene and indole moieties, efficiently transfers hydrogen from methanol to aldehydes, converting them into 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 and scalable to gram-scale production, and reduces energy consumption, highlighting its potential for advancing catalytic transfer hydrogenation.