Improved Synthetic Route to Dexamethasone Acetate from Tigogenin

In the synthesis of dexamethasone acetate from tigogenin, the introduction of the 17α-hydroxy-16α-methyl and the 1,4-diene moieties was improved. For the introduction of the 17α-hydroxy-16α-methyl moiety, the key step, epoxidation, was accomplished in high yield with peracetic acid in a buffer solut...

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Bibliographic Details
Published in:Organic process research & development 1997-11, Vol.1 (6), p.420-424
Main Authors: Ohta, Tetsuo, Zhang, Huyue, Torihara, Yoshitaka, Furukawa, Isao
Format: Article
Language:English
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Summary:In the synthesis of dexamethasone acetate from tigogenin, the introduction of the 17α-hydroxy-16α-methyl and the 1,4-diene moieties was improved. For the introduction of the 17α-hydroxy-16α-methyl moiety, the key step, epoxidation, was accomplished in high yield with peracetic acid in a buffer solution of sodium acetate and acetic acid (overall yield from 17-ene substrate to 17α-hydroxy-16α-methyl intermediate:  95.3%). Then the introduction of the 1,4-diene in the A-ring was greatly improved by bromination−dehydrobromination, in which dehydrobromination proceeded smoothly in a solvent system that was a mixture of DMF and 6% of water (82.6% isolated yield of 1,4-diene based on 3-oxo compound).
ISSN:1083-6160
1520-586X
DOI:10.1021/op9700338