Bufadienolides. 3. A Synthetic Route to Isocardenolides

George Pettit, Brian Green, Arun K. Das Gupta, Philip A. Whitehouse, John P. Yardley

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

A Bestmann reaction employing 3β-acetoxy-20-oxo-21-iodo-5-pregnene (2) and carbomethoxymethylenetriphenylphosphorane was used to complete a synthesis of methyl 3β-acetoxy-2-oxo-21-nor-5-imns-22-choladienate (1), which upon irradiation in sunlight gave cis isomer 5. Similarly, 3β-acetoxy-20-oxo-21-iodo-5,16-pregna-diene (6) was converted into trans side-chain olefin 7 and cis side-chain olefin 8. Palladium-catalyzed hydrogenation of triene 8 resulted in methyl 3-acetoxy-20-oxo-21-nor-5a-cholanate (9a) accompanied by small amounts of the corresponding 3-deoxy derivative 9b and 3β-acetoxy-20-hydroxy-21-nor-5a-cholanic acid γ-lactone (24 å 20). Subjecting triene 8 to sodium borohydride reduction in ethanol yielded isocardanolide 10. The principal objective, synthesis of isocardenolide 11, was realized by selective reduction of ketone 5 with sodium borohydride in dimethylformamide.

Original languageEnglish (US)
Pages (from-to)1381-1384
Number of pages4
JournalJournal of Organic Chemistry
Volume35
Issue number5
DOIs
StatePublished - May 1 1970

ASJC Scopus subject areas

  • Organic Chemistry

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