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Someone in the anabolic forumasked me to design a synthesis for what I think is THG. Keep in mind that this isn't something that someone could do without a fully equipped lab and access to chemical reagents.
synthesis in 4 steps from gestrinone (probably commercially available):
1. Protect 3-carbonyl as the ethylene ketal (ethylene glycol + TsOH, remove H2O as formed)
2. Reduce 17-ethyne triple bond to a double bond with refluxing LiAlH4 in THF.
3. Reduce 17-ethenyl double bond with [Rh(NBD)(dppb)]BF4 (selective hydrogenating agent for allylic alcohols. None of the other double bonds are allylic alcohols and thus should not be affected).
4. Remove ketal protecting group from 3-one with TsOH in methanol (carefully so as not to eliminate the 17-OH).
VOILA. THG.
The [Rh(NBD)(dppb)]BF4 selective hydrogenating agent might actually be able to reduce the triple bond directly while sparing the other double bonds. If that turned out to be the case, the synthesis becomes a single step since the LiAlH4 step would not be needed and protection scheme needed to protect the 3-one from the LiAlH4 would also not be needed.
synthesis in 4 steps from gestrinone (probably commercially available):
1. Protect 3-carbonyl as the ethylene ketal (ethylene glycol + TsOH, remove H2O as formed)
2. Reduce 17-ethyne triple bond to a double bond with refluxing LiAlH4 in THF.
3. Reduce 17-ethenyl double bond with [Rh(NBD)(dppb)]BF4 (selective hydrogenating agent for allylic alcohols. None of the other double bonds are allylic alcohols and thus should not be affected).
4. Remove ketal protecting group from 3-one with TsOH in methanol (carefully so as not to eliminate the 17-OH).
VOILA. THG.
The [Rh(NBD)(dppb)]BF4 selective hydrogenating agent might actually be able to reduce the triple bond directly while sparing the other double bonds. If that turned out to be the case, the synthesis becomes a single step since the LiAlH4 step would not be needed and protection scheme needed to protect the 3-one from the LiAlH4 would also not be needed.
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