The PCP pincer complex, IrH2{C6H3-2,6-(CH2P-t-Bu2)2} (1) catalyzes the transfer dehydrogenation of primary and secondary alcohols. Dehydrogenation occurs across the CO bond rather than the CC bonds and the corresponding aldehydes or ketones are obtained as the sole products arising from the dehydrogenation reactions. Methanol is an exception to this pattern of reactivity and undergoes only stoichiometric dehydrogenation with 1 to give the carbonyl complex, Ir(CO){C6H3-2,6-(CH2P-t-Bu2)2} (2). The products are obtained in nearly quantitative yields when the reactions are carried out in toluene solutions. Under the same conditions, 2,5-hexanediol is converted to the annulated product, 3-methyl-2-cyclopenten-1-one which has been isolated in 91% yield in a preparative scale reaction.Key words: alcohol, dehydrogenation, ketones, iridium pincer complex, annulation.
An electron poor iridium pincer complex for catalytic alkane dehydrogenation