Transfer Hydrogenation of Unsaturated Compounds

The reaction of methanol with ethanol was performed by Ueda et al. " " over a MgO catalyst with an ethanol/methanol molar ratio of 1/20 at a temperature of 380 °C. The main products are propanol and 2-methyl propanol. The yields are 17.9 and 20.3 mol%, respectively, based on the charged ethanol at a ethanol conversion of 50.3%. The reaction may consist of several elementary steps such as aldol-type condensation, dehydrogenation of ethanol and/or methanol, hydrogenation of unsaturated compounds produced by the aldol-type condensation, and hydrogen transfer reaction from alcohol to aldehyde. Further detailed information is required to understand the reaction. 

Dissymmetric ferrocenyldiphosphines have been synthesized from (R)-(+)-N, N -dimethylaminoethylferrocene. The diphosphines have been used as ligands in asymmetric transfer hydrogenation of acetophenone in the presence of ruthenium catalysts.297 Asymmetric transfer hydrogenation of a,/S-unsaturated aldehydes with Hantzsch dihydropyridines and a catalytic amount of MacMillan imidazolidinone salt (12) leads to the saturated carbonyl compounds in high yields and excellent chemo-and enantio-selectivities.298 ... 

Precursor of Useful Chiral Ligands. OPEN is widely used for the preparation of chiral ligands. Organometallic compounds with these ligands act as useful reagents or catalysts in asymmetric induction reactions such as dihydroxylation of olefins, transfer hydrogenation of ketones and imines, Diels-Alder and aldol reactions, desymmetrization of meso-diols to produce chiral oxazolidinones, epoxidation of simple olefins, benzylic hydroxylation, and borohydride reduction of ketones, imines, and a,p-unsaturated carboxylates. ... 

Retro ene reaction or retro ene fragmentation involves the intramolecular thermolysis of unsaturated compounds by the transfer of a y-hydrogen to the... 

Sasson Y, Blum I (1971) Homogenous catalytic transfer-hydrogenation of a, fl-unsaturated carbonyl compounds by dichl(xotris(triphenylphosphine)ruthenium(ll). Tetrahedron Lett 12 2167-2170... 

The homogeneous transfer-hydrogenation of a/ -unsaturated carbonyl compounds using ruthenium catalysts has been described, and is shown in Scheme 88. 

Asymmetric hydrogenation of heteroaromatic compounds provides a straightforward synthetic pathway to access enantioenriched heterocycles, which are of great importance in the synthesis of pharmaceuticals and natural products. Rueping et al. reported several examples of enantioselective cascade transfer hydrogenation reaction of heteroaromatic substrates under metal-free conditions [19,20]. The same group also developed a cascade reaction between enamines 42 and oc,P-unsaturated... 

L = P(CH3)3 or CO, oxidatively add arene and alkane carbon—hydrogen bonds (181,182). Catalytic dehydrogenation of alkanes (183) and carbonylation of bensene (184) has also been observed. Iridium compounds have also been shown to catalyse hydrogenation (185) and isomerisation of unsaturated alkanes (186), hydrogen-transfer reactions, and enantioselective hydrogenation of ketones (187) and imines (188). 

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