Titanocene Dichloride as a Convenient Catalyst for the Diastereoselective Oxidation of 2-Substituted 1,3-Dithianes and 1,3-Dithiolanes

Abstract

Cp₂TiCl₂ is an efficient catalyst for the diastereoselective mono-oxidation of 2-substituted 1,3-dithianes and 1,3-dithiolanes by tert-butyl hydroperoxide; comparable stereoselectivities and better yields than Ti(i-PrO)₄ were obtained. Activities are similar, provided activated 4Å molecular sieves are present in the titanocene-promoted process. Furthermore, Cp₂TiCl₂ is a more moisture stable compound than Ti(i-PrO)₄ and therefore can be used in catalytic amounts of 1 mol%.

Key words

diastereoselectivity - oxidations - metallocenes - sulfoxides - titanium

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The same batch of Cp₂TiCl₂ was used for several months without taking any particular precaution.

23

Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publications no CCDC-175498. Copies of data may be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 EZ, UK [Fax: [phone]; e-mail: [e-mail]].