Addition of the sulfur ylide generated from trimethylsulfoxonium iodide and NaH to the 20-ethylene ketal of pregnane-3,20-dione (I) furnished the spiro oxirane derivative (II). This was reduced to the tertiary alcohol (III) by means of LiAlH4 in refluxing THF. Then, acid hydrolysis of the ethylene ketal function of (III) provided the title compound. Alternatively, the intermediate ketal (III) was prepared by addition of methylmagnesium bromide to ketone (I), followed by chromatographic separation of the resultant mixture of 3-alpha and 3-beta methyl adducts.
Starting from the unprotected diketone (IV), selective addition of dimethyloxosulfonium methylide to the 3 keto group furnished oxirane (V). This was then reduced to the title alcohol by treatment with tributylstannyl hydride and AIBN.
Regioselective addition of dimethylsulfoxonium methylide to 5-alpha-pregnane-3,20-dione (I) gave the epoxide (II). Opening of the epoxide ring of (II) with sodium methoxide produced the hydroxy ether (III). Bromination of (III) with Br2 in the presence of a catalytic amount of HBr afforded bromo ketone (IV). This was then condensed with imidazole (V) in refluxing acetonitrile to furnish the title compound.
Regioselective addition of dimethylsulfoxonium methylide to 5-alpha-pregnane-3,20-dione (I) gave the epoxide (II). Opening of the epoxide ring of (II) with sodium methoxide produced the hydroxy ether (III). Bromination of (III) with Br2 in the presence of a catalytic amount of HBr afforded bromo ketone (IV). This was then condensed with 6-hydroxyquinoline (V) in the presence of potassium tert-butoxide to furnish the quinolinyl ether (VI). The quinoline ring was then oxidized with m-chloroperbenzoic acid, yielding the title N-oxide.