Asymmetric Hydrogenation with Modified Raney Nickel. I. Studies on Modified Hydrogenation Catalyst. II

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Abstract 1. Raney nickel catalyst treated with optically active glutamic acid has the property of catalyzing the hydrogenation of carbonyl compounds asymmetrically with high reproducibility and efficiency. 2. Excellent results were obtained in the hydrogenation of methyl acetoacetate to optically active methyl 2-hydroxybutyrate in the presence of Raney nickel catalyst treated with l- or d-glutamic acid. 3. The capacity for asymmetric hydrogenation was strongly dependent upon the pH of the modifying solution. The highest capacity was obtained when modifying solutions were adjusted to pH 4.8∼5.5. 4. With elevation of the temperature of the modifying process, the asymmetric capacity of the catalyst decreased markedly, nearly disappearing at 60°C, and yielding products with reverse optical rotation above 80°C. 5. The asymmetric capacity was independent of the concentration of the modifying solution within the range of 6 to 0.0625%. 6. Hydrogenation in the presence of catalyst modified with d-glutamic acid yielded a product with reverse optical rotation to that obtained when l-glutamic acid was used. 7. Asymmetric yield of the reducing product of methyl acetoacetate by the catalyst treated with Glu was varied with the relative amount of the substrate and the catalyst.