Iridium (I) and phase-transfer catalyzed hydrogen-transfer reduction of ketones using potassium fluoride on alumina as a base

Abstract

The hydrogen transfer reduction of alkyl aryl (heteroaryl) ketones readily occurs at 82°C in a solid—liquid biphasic system when using 2-propanol as hydrogen donor, potassium fluoride on alumina (50 wt.%) as a base, [Ir(COD)Cl]₂ as the metal catalyst and 18-crown-6 as the phase-transfer agent. The molar ratio of ketone : [Ir] : F⁻] : 18-crown-6 was 200:1:5:2. A number of alkyl aryl, and alkyl heteroaryl carbinols have been prepared in 73–84% isolated yield under HTR-PTC conditions.