Reduction of Organic Compounds with NaBH4-Transition Metal Salt Systems. IV. Selective Hydrogenation of Olefines in Unsaturated Esters

Hydrogenation of unsaturated esters was performed with NaBH4-transition metal salt systems. Nickel, cobaltous and cupric salts were effective metal salts for reduction of olefinic esters. Hydrogenation of the olefinic bonds proceeded quantitatively to afford the corresponding saturated esters when using one of the following pairs : NiCl2·6H2O (0.1 mole)-NaBH4 (2 moles), CoCl2·6H2O (0.25 moles)-NaBH4 (10 moles) and CuCl2.2H2O (0.3 moles)-NaBH4 (6 moles) per mole of I.