Ruthenium tetroxide oxidation of Grundmann's ketone derived from vitamin D3

The reaction of Grundmann's ketone 2a with ruthenium tetroxide, generated in situ from ruthenium trichloride and sodium metaperiodate, has been investigated. In addition to the main 25-hydroxylated compound 2b the minor oxidation products have been isolated and identified. The examined catalytic process results in the oxidation of methylene groups and hydroxylation at teriary positions occurring with retention of configuration.