Iridium–aluminium trichloride co-catalysed hydroformylation–acetalization of olefins with H2O as the hydrogen source

The tandem hydroformylation–acetalization of olefins with H2O as the hydrogen source was accomplished over an Ir(I)-catalyst using the phased warming strategy. Due to the release of protons by AlCl3-hydrolysis equilibrium, the tandem reaction was significantly enhanced. The conversion of 1-hexene was 100% and the selectivity for oxo-products was 89%, where 91% of acetals was obtained. Moreover, the hydrogenation by-products were detected to be less than 3%, showing that H2O as the hydrogen source inhibited the hydrogenation of olefins in this tandem reaction. Moreover, isotope-labeling experiments confirmed that water was the hydrogen source, and the key Ir–H active species for hydroformylation were captured by high-pressure 1H NMR spectroscopy analyses.