p-Toluenesulfonic acid → HCID 70614944, compound

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Reaction Steps

Hydrogenation of 19-hydroxy-5-androstenes by means of 10% palladium on charcoal results in good yields of the corresponding 19-hydroxy-5α-androstanes. Suitable steroid substrates which fulfill the 5-ene requirement for stereoselectivity during the reduction include 3β,19-dihydroxy-5-androstenes, 19-hydroxy-5-androsten-3-ones, 19-hydroxy-5-androsten-3-one 3-cyclic ethyleneketal and 3-alkoxy-3,5-androstadien-19-ols. Typical reduction conditions utilize 2-10parts of the steroid substrate to 1 part catalyst with methanol or ethanol as solvent and hydrogen pressures ranging from 1 to 3 atmospheres. In this manner 1β,17α-dimethyl-5-androstene-3β,17β,19-triol, 7α-methyl-19-tetrahydropyranyloxy-5-androsten-3β,17β-diol and 6α-methyl-3β,19-dihydroxy-5-androsten-17-one are reduced to 1β,17α-dimethyl-5α-androstane-3β,17β,19-triol, 7α-methyl-19-tetrahydropyranyloxy-5α-androstan-3β,17β-diol and 6α-methyl-3β,19-dihydroxy-5α-androstan-17-one, respectively. 19-Hydroxy-1α-methyl-4-androstene-3,17-dione is converted to its cyclic ethyleneketal by heating at reflux temperatures with p-toluenesulfonic acid and ethyleneglycol in benzene. The ketal which forms is then reduced and hydrolyzed to form 19-hydroxy-1α-methyl-5α-androstan-3,17-dione. 17β,19-Di(trimethylsiloxy)-4-androsten-3-one can be converted to the methyl enol ether by the action of trimethylorthoformate, p-toluenesulfonic acid and methanol in tetrahydrofuran. The 3-methoxy-3,5-diene which forms is then catalytically reduced to yield 17β,19-di(trimethylsiloxy)-5α-androstan-3-one. The ethylenol ether of 19-hydroxy-4-androsten-3,17-dione acetate can also be reduced to yield 19-hydroxy-5α -androstane-3,17-dione acetate.

Provenance & Evidence