Regioselective hypervalent iodine-induced Favorskii rearrangement of 3-oxo-5β-steroids

• Treatment of 3-oxo-5β-steroids with DIB/KOH produced a Favorskii rearrangement.
• 3β-Methoxycarbonyl-5β-4-norsteroids are produced in good yields.
• The observed regioselectivity was justified in terms of the Semi-benzylic mechanism.
• The obtained compounds were characterized by NMR and X-ray Diffraction.

Treatment of 3-oxo-5β-steroids with diacetoxyiodobenzene/KOH triggered a fast and regioselective Favorskii rearrangement that exclusively led to 3β-methoxycarbonyl-5β-4-norsteroids in good yields. The outcome of the reaction indicates that although both Cyclopropanone and Semi-benzylic pathways are possible, in the case of 3-oxo-5β-steroids, only the last participates. Unambiguous characterization of the products was achieved by NMR and X-ray Diffraction studies.

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