6960 J. Org. Chem. 2009, 74, 6960–6964 Published on Web 08/17/2009 DOI: 10.1021/jo9008657 r 2009 American Chemical Society pubs.acs.org/joc Highly Chemo- and Regioselective Reduction of Aromatic Nitro Compounds Using the System Silane/Oxo-Rhenium Complexes Rita G. de Noronha, † Carlos C. Rom~ ao, † and Ana C. Fernandes* ,‡ † Instituto de Tecnologia Quı´mica e Biol  ogica, Universidade Nova de Lisboa, Av. da Rep  ublica - EAN, 2781- 157 Oeiras, Portugal, and ‡ Centro de Quı´mica Estrutural, Complexo I, Instituto Superior T ecnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal anacristinafernandes@ist.utl.pt Received May 8, 2009 The reduction of aromatic nitro compounds to the corresponding amines with silanes catalyzed by high valent oxo-rhenium complexes is reported. The catalytic systems PhMe 2 SiH/ReIO 2 (PPh 3 ) 2 (5 mol %) and PhMe 2 SiH/ReOCl 3 (PPh 3 ) 2 (5 mol %) reduced efficiently a series of aromatic nitro compounds in the presence of a wide range of functional groups such as ester, halo, amide, sulfone, lactone, and benzyl. This methodology also allowed the regioselective reduction of dinitrobenzenes to the corresponding nitroanilines and the reduction of an aromatic nitro group in presence of an aliphatic nitro group. Introduction The selective reduction of aromatic nitro compounds is a useful reaction for the synthesis of amines, important inter- mediates in the production of many pharmaceuticals, agro- chemicals, dyes, polymers, photographic and rubber materials, and chelating agents. Numerous methods have been developed to accomplish this transformation including catalytic hydrogenation, 1 sodium borohydride/catalyst, 2 hydrazine/catalyst, 3 and metals such as iron, tin, or zinc. 4 Over the last years, a variety of other chemical systems such as Mo(CO) 6 /DBU, 5 Pd(OAc) 2 /PMHS, 6 Sm/I 2 , 7 Sm/1,1 0 -dioctyl-4,4 0 -bipyridi- nium dibromide, 8 Sm/NH 4 Cl, 9 Cu nanoparticles/ HCOONH 4 , 10 S 8 /NaHCO 3 , 11 and HI 12 have been reported. Enzymatic reduction of aromatic nitro compounds with molybdoenzymes is believed to proceed by oxygen atom transfer from the nitrogen center to the Mo IV O center of the enzyme. 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