Evidence for the existence of a cyclic ruthenium (VI) diester as an intermediate in the oxidative scission of (-)-α-pinene with RuO4

Article abstract of DOI:10.1016/0040-4039(95)00954-B

The reaction of (-)-α-pinene (1) with RuO₄ in CCl₄ at room temperature affords the ketoaldehyde 3 as the sole product. Evidence is reported that the oxidative scission of the olefinic substrate to 3 proceeds through a ruthenium (VI) diester intermediate for which we propose structure 2 on the basis of spectral evidence and comparison with the osmium-containing analogue of 2, synthesised by reaction of (-)-α-pinene with OsO₄ in dioxane and whose structure has been determinated by single crystal X-ray diffraction analysis. Compound 2 was also shown to be an intermediate compound in the RuO₄ oxidation of (-)-α-pinene performed in acetone-water (2:1) which gives α-ketol 4 as the sole oxidation product.