Bufadienolides. 10. 3β-acetoxy-14β,21-epoxy-5β-bufanolide and related lactones

John C. Knight, George Pettit, Peter Brown

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Methyl 3β-pyranyloxy-(21S)-methoxy-14β,21-epoxy-5β-(20S)-norcholanate (6a) and the axial acetal 6b each gave isodigitoxigenin (3a) on treatment with hydrochloric acid in aqueous acetic acid. Extension of this reaction to cholanate ester 7b gave 3β-acetoxy-14β,21-epoxy-5β-bufanolide (4). The epoxide 9 prepared from 3β-acetoxy-14β,21-epoxy-5β-chol-20(21)-enic acid (8b) spontaneously cyclized to give γ-lactones of type 11 rather than δ-lactone derivatives. In another potential approach to bufadienolides, 3β-pyranyloxy-23-mesyloxy-14β,21-epoxy-(21S)-methoxy-5β-(20/S)- norcholane (7d) was converted into 3β-acetoxy-14β,21-epoxy-20-formylpregn-20(21)-ene (15a). Condensation of aldehyde 15a with malonic acid took an unexpected course which culminated in formation of olefin 18.

Original languageEnglish (US)
Pages (from-to)1415-1419
Number of pages5
JournalJournal of Organic Chemistry
Volume35
Issue number5
StatePublished - 1970

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Bufanolides
Lactones
Acetals
Hydrochloric Acid
Epoxy Compounds
Alkenes
Aldehydes
Acetic Acid
Condensation
Esters
Derivatives
Acids

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Bufadienolides. 10. 3β-acetoxy-14β,21-epoxy-5β-bufanolide and related lactones. / Knight, John C.; Pettit, George; Brown, Peter.

In: Journal of Organic Chemistry, Vol. 35, No. 5, 1970, p. 1415-1419.

Research output: Contribution to journalArticle

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abstract = "Methyl 3β-pyranyloxy-(21S)-methoxy-14β,21-epoxy-5β-(20S)-norcholanate (6a) and the axial acetal 6b each gave isodigitoxigenin (3a) on treatment with hydrochloric acid in aqueous acetic acid. Extension of this reaction to cholanate ester 7b gave 3β-acetoxy-14β,21-epoxy-5β-bufanolide (4). The epoxide 9 prepared from 3β-acetoxy-14β,21-epoxy-5β-chol-20(21)-enic acid (8b) spontaneously cyclized to give γ-lactones of type 11 rather than δ-lactone derivatives. In another potential approach to bufadienolides, 3β-pyranyloxy-23-mesyloxy-14β,21-epoxy-(21S)-methoxy-5β-(20/S)- norcholane (7d) was converted into 3β-acetoxy-14β,21-epoxy-20-formylpregn-20(21)-ene (15a). Condensation of aldehyde 15a with malonic acid took an unexpected course which culminated in formation of olefin 18.",
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N2 - Methyl 3β-pyranyloxy-(21S)-methoxy-14β,21-epoxy-5β-(20S)-norcholanate (6a) and the axial acetal 6b each gave isodigitoxigenin (3a) on treatment with hydrochloric acid in aqueous acetic acid. Extension of this reaction to cholanate ester 7b gave 3β-acetoxy-14β,21-epoxy-5β-bufanolide (4). The epoxide 9 prepared from 3β-acetoxy-14β,21-epoxy-5β-chol-20(21)-enic acid (8b) spontaneously cyclized to give γ-lactones of type 11 rather than δ-lactone derivatives. In another potential approach to bufadienolides, 3β-pyranyloxy-23-mesyloxy-14β,21-epoxy-(21S)-methoxy-5β-(20/S)- norcholane (7d) was converted into 3β-acetoxy-14β,21-epoxy-20-formylpregn-20(21)-ene (15a). Condensation of aldehyde 15a with malonic acid took an unexpected course which culminated in formation of olefin 18.

AB - Methyl 3β-pyranyloxy-(21S)-methoxy-14β,21-epoxy-5β-(20S)-norcholanate (6a) and the axial acetal 6b each gave isodigitoxigenin (3a) on treatment with hydrochloric acid in aqueous acetic acid. Extension of this reaction to cholanate ester 7b gave 3β-acetoxy-14β,21-epoxy-5β-bufanolide (4). The epoxide 9 prepared from 3β-acetoxy-14β,21-epoxy-5β-chol-20(21)-enic acid (8b) spontaneously cyclized to give γ-lactones of type 11 rather than δ-lactone derivatives. In another potential approach to bufadienolides, 3β-pyranyloxy-23-mesyloxy-14β,21-epoxy-(21S)-methoxy-5β-(20/S)- norcholane (7d) was converted into 3β-acetoxy-14β,21-epoxy-20-formylpregn-20(21)-ene (15a). Condensation of aldehyde 15a with malonic acid took an unexpected course which culminated in formation of olefin 18.

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