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Ammonium-Directed Oxidation of Cyclic Allylic and Homoallylic Amines

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posted on 04.09.2009, 00:00 by Christopher W. Bond, Alexander J. Cresswell, Stephen G. Davies, Ai M. Fletcher, Wataru Kurosawa, James A. Lee, Paul M. Roberts, Angela J. Russell, Andrew D. Smith, James E. Thomson
The ammonium-directed olefinic oxidation of a range of cyclic allylic and homoallylic amines has been investigated. Functionalization of a range of allylic 3-(N,N-dibenzylamino)cycloalk-1-enes with m-CPBA in the presence of Cl3CCO2H gives exclusively the corresponding syn-epoxide for the 5-membered ring (>99:1 dr), the anti-epoxide for the 8-membered ring (>99:1 dr), and predominantly the anti-epoxide for the 7-membered ring (94:6 dr). Oxidation of the homoallylic amines 3-(N-benzylamino)methylcyclohex-1-ene and 3-(N,N-dibenzylamino)methylcyclohex-1-ene gave, in both cases, the corresponding N-protected 1,2-anti-2,3-syn-3-aminomethylcyclohexane-1,2-diol with high levels of diastereoselectivity (≥90:10 dr). The versatile synthetic intermediates resulting from these oxidation reactions are readily transformed into a range of amino diols.