Development of Titania-supported Iridium Catalysts for the Acceptor-less Dehydrogenative Synthesis of Benzoxazoles

Iridium catalysts supported on anatase with high surface area showed excellent activities for the acceptor-less dehydrogenation synthesis of benzoxazoles from 2-aminophenol and primary alcohols. The catalytic activity greatly depended titania supports, iridium precursors, loading species. Catalysts JRC (Japan Reference Catalyst)-TIO-10 highest dehydrogenative reaction. Preparation using [Ir(cod)Cl]2 (cod = 1,5-cyclooctadiene) as an precursor resulted in higher than Ir(acac)3 (acac acetylacetonate). Various alcohols were reacted to give corresponding moderate yields. catalyst could be recycled without significant loss activity, no leaching species occurred into solution. hot filtration test strongly suggested that catalysis occurs surface. Highly dispersed less 2 nm diameter, which reduced at low temperature, responsible activity.