Iridium chloride, transfer hydrogenation catalyst

Selective reduction to hydroxylamine can be achieved in a variety of ways the most widely applicable systems utilize zinc and ammonium chloride in an aqueous or alcoholic medium. The overreduction to amines can be prevented by using a two-phase solvent system. Hydroxylamines have also been obtained from nitro compounds using molecular hydrogen and iridium catalysts. A rapid metal-catalyzed transfer reduction of aromatic nitroarenes to N-substituted hydroxylamines has also been developed the method employs palladium and rhodium on charcoal as catalyst and a variety of hydrogen donors such as cyclohexene, hydrazine, formic acid and phosphinic acid. The reduction of nitroarenes to arylhydroxyl-amines can also be achieved using hydrazine in the presence of Raney nickel or iron(III) oxide. ... 

Hydrogen transfer reactions are catalyzed by several iridium complexes, including the dimethyl sulfoxide (DMSO) complexes cis- and trans-[Ir(Cl)4(DMSO)2]", [Ir(Cl)3(DMSO)3] and [lr(H)-(Cl)2(DMSO)3], as well as the cyclooctadiene (cod) complexes [Ir(Cl)(cod)]2 and [Ir(3,4,7,8-Me4phen)(cod)], and tra 5-[Ir(Cl)(CO)(PPh3)2]. Vaska s complex catalyzes the conversion of p-methoxybenzoyl chloride to the corresponding aldehyde. The dimethyl sulfoxide iridium(III) complexes catalyze hydrogen transfer from propan-2-ol to unhindered cyclohexanones to yield cyclohexanols, while the cod complexes serve as catalysts in the transfer of hydrogen from propan-2-ol to alkenes, ketones and a,/3-unsaturated ketones. ... 

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