fermium
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Reduction of androstene di- and tri-ones
Here is the selective borohydride reduction of androstenedione as described by SANDMEYER in a previous thread:
He can reduce the simple keto group with NaBH4 in the presence of the a,b-unsaturated ketone elsewhere. Hydride is a hard nucleophile, it reacts
faster at C=O (1,2) than in 1,4-fashion. I even have the reference (NaBH4 for C=O to C-OH) for this particular compound: With NaBH4: Norymberski;
Woods; J. Chem. Soc.; 1955; 3426,3429.
My question is, what will be the product(s) if the androstene-3,6,17-TRIONE shown above is used as the reactant instead of the dione?
Will it be the same reaction in the sense that the C-17 carbonyl will be reduced whereas the C-3 and C-6 carbonyls will not because they form a
conjugated system with the alkene?
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Sandmeyer
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The reference I provided suggests that the saturated ketone gets reduced to alcohol in the presence of an enone functional group (which is left
intact) elswere on the molecule, but I haven't checked any details other than those seen in Beilstein since J. Chem. Soc papers are unavailable to me.
It is hard to say in this situation - I guess you'll have to try the reduction and characterise the products.
Meerwein-Ponndorf-Verley reduction is a nice alternative to NaBH4, but I don't know how selective it would be in this case, and I'm unable to search
the litterature at the moment.
[Edited on 31-12-2005 by Sandmeyer]
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