Platinum supported on TiO2 as a new selective catalyst on heterogeneous hydrogenation of α,β-unsaturated oxosteroids

This paper describes the photochemical deposition of platinum onto TiO2 surface and the full characterization of the catalysts using BET, XPS and TEM techniques. The 1 and 3 wt. % Pt/TiO2 catalysts reveal high activity with 70% and 96% of α-diastereoselectivity in the hydrogenation of the carbon–carbon double bond of the α,β-unsaturated oxosteroids 4-androstene-3,17-dione, and 3β-acetoxypregna-5,16-dien-20-one, respectively. Using higher temperature and pressure, the catalysts promote the further reduction of C-3 carbonyl group. Catalyst recovering and recycling is easily achieved with no appreciable lost of catalytic activity after five subsequent runs.

The Pt/TiO2 catalysts prepared by photochemical deposition of platinum onto titania are very selective (70% and 96% of α-diastereoselectivity) for the hydrogenation of the carbon–carbon double bond of the α,β-unsaturated oxosteroids, 4-androstene-3,17-dione (I) and 3β-acetoxypregna-5,16-dien-20-one (II).Figure optionsDownload high-quality image (28 K)Download as PowerPoint slideResearch highlights▶ Pt nanoparticles (4–5 nm) are supported over TiO2 by photochemical deposition ▶ Pt/TiO2 is an efficient catalyst for the hydrogenation of α,β-unsaturated oxosteroids ▶ The activity and selectivity of these catalysts are pressure independent but the regioselectivity can be modulated by temperature ▶ The α-diastereoselectivity was outstanding, comparable to the homogeneous process ▶ No decrease of activity or selectivity is observed after using the catalyst in five consecutive cycles.