Hydrogenation of unhindered cyclohexanones with rhodium catalyst in isopropyl alcohol or tetrahydrofuran in the presence of hydrochloric acid gives excellent yields of axial alcohols. Steroidal 3,17- and 3,20-diones are selectively hydrogenated at C-3 to give the corresponding 3-axial-hydroxy ketones in high yields.
The catalytic reduction of several β-ferrocenyl-α,β-unsaturated ketones was investigated using Urushibara nickel A (U-Ni-A) or precipitated nickel (ppt-Ni) as the catalyst, and their relative reactivities toward the catalytic reduction were discussed in comparison with those of the phenyl analogs. Some anomalies observed in the NMR spectra of the reduction products was also discussed.
MASAYOSHI ISHIGE, MICHIO SHIOTA, and FUMIYO SUZUKI. Can. J. Chem. 54, 2581 (1976). The title compounds are conveniently obtained from the corresponding diones by the stereoselective hydrogenation with Urushibara nickel A catalyst in cyclohexane.MASAYOSHI ISHIGE, MICHIO SHIOTA et FUMIYO SUZLIKI. Can. J. Chem. 54, 2581 (1976. On peut obtenir facilement les composts mentionnts dans le titre en partant des diones correspondantes et en les soumettant i une hydrogtnation sttrtostlective en prtsence d'un catalyseur de nickel A d'urushibara dans le cyclohexane.[Traduit par le journal] Introduction 3a-Hydroxy-5a-cholestan-6-one (3) may be prepared by various routes (1-6) but the yields are always quite low even if the experiments are done carefully. There is little information about 3a-hydroxy-5a-cholestan-7-one (5) in the literature (7, 8) and a convenient preparation is not available.We have reported earlier (9) that epicholestan01 (5a-cholestan-3a-01) and epicholesterol (5-cholesten-3a-01) are readily prepared from the corresponding steroidal ketones in good yields by the nickel catalyzed hydrogenation in hydrocarbon solvents at low temperature under high pressure. It is of interest that the more stable equatorial 30-01 is not the predominant product. We attempted to apply this reduction method for the preparation of the title compounds.
Catalytic hydrogenation of 5α-cholestan-3-one was investigated to examine the factors influencing the selective formation of the axial 3α-ol and it has been found that the most satisfactory yield of 3α-ol is realized using Urushibara nickel A, the nickel catalyst treated by acid, in hydrocarbon solvents at lower temperatures under high pressure. Preparation of epicholestanol and epicholesterol by this method is described.
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