Resolution of conflicting migratory reports in ring expansion of 3-keto steroids to oxygen and nitrogen

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Abstract
The migration of C-2 and/or C-4 to O or N in the Beckmann, Schmidt, and Baeyer–Villiger reactions of 3-keto steroids has been studied with the aid of 13Cmr spectroscopy. Authentic specimens of the eight possible lactone and lactam products from both 5α- and 5β-cholestan-3-one have been prepared; their physical properties and 13Cmr assignments are given. Seven ring expansion reactions reported to give only one product have been found to give both possible migration products. The much studied reactions of 5α-cholestane-3,6-dioneand its derivatives have been reexamined. The results emphasize again the necessity of using 13C spectra both as an analytical tool and as the best criterion of purity in work with these molecules.