Manganese(III) acetate based oxidation of substituted α′-position on cyclic α,β-unsaturated ketones
作者:Cihangir Tanyeli、Çigdem Iyigün
DOI:10.1016/s0040-4020(03)01094-9
日期:2003.9
Selective oxidation of the tertiary α′-position on various 2-cyclopentenone, 2-cyclohexenone and aromatic ketone derivatives with manganese(III) acetate is described.
alpha-Mono- or alpha-dialkylated aldehydes undergo cyclotrimerization in the presence of dibromotriphenylphosphorane (PPh(3)Br(2)) to afford cyclopentenones or tetrasubstituted tetrahydrofurans in good yields. These transformations proceed by a tandem aldol dimerization/Nazarov reaction or a tandem aldol dimerization/Prins cyclization.
The enantio selective resolution of various quaternary alpha'-acetoxy alpha,beta-unsaturated cyclohexenones and cyclopentenones was performed with the commercially available enzyme CCL in pH = 8.0 phosphate buffer. Various parameters that would affect the enantioselectivities were tested and the best enzymatic resolution conditions were found to afford the enantiomerically enriched quaternary acetoxylated substrates with high ee varying between 36% and 99%. (c) 2005 Elsevier Ltd. All rights reserved.
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