C-22 ketals related to the sapogenins
作者： H. Hirschmann , Frieda B. Hirschmann
DOI: 10.1016/0040-4020(58)80020-4
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摘要: Abstract Reduction of 5,6-dihydrokryptogenin diacetate with Raney nickel in ethanol reduced the 16-ketone group and gave a mixture 22-ethyl ketal hemiketal. Both undergo elimination reactions very readily to yield Δ22-bond isomer pseudotigogenin diacetate. The conversions are reversible catalyzed by acetic acid neutral solution calcium sulfate other surfaces. Alkaline hydrolysis followed cyclization converted both Δ22-olefin tigogenin. relative stabilities epimers at C-22 discussed related stereo-chemistry sapogenins cyclopseudosapogenins.
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