Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements

George Pettit, T. R. Kasturi, John C. Knight, John Occolowitz

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Several methods were developed for converting isodigitoxigenin (2a) into methyl acetals 4b and 4c. Of these, methanolysis (followed by acetylation) of isodigitoxigenin in the presence of p-toluenesulfonic acid proved most useful. Each isomer reached an equilibrium corresponding to ca. 3:1 acetal 4c to 4b within 15 min in benzene containing p-toluenesulfonic acid. Addition of dihydropyran to the equilibrium mixture resulted in excellent conversion into vinyl ether 5a. Heating either acetal 4b or 4c in benzene containing p-toluenesulfonic acid led to a skeletal rearrangement culminating in formation of C-norcardenolide 6. In addition to results of physical measurements, the structure of spiran 6 was confirmed by degradation to methyl ketone 8. Similar rearrangement of isodigitoxigenin gave spiran 9 accompanied by C-norcardenolide 6. Treating lactone 9 with p-toluenesulfonic acid in methanol-water provided acetals 10a and 10b, which on further contact with p-toluenesulfonic acid in refluxing benzene gave lactone 9 and cardenolide 6. Evidence underlying the stereochemical assignments noted for structures 4, 9, and 10 was also discussed.

Original languageEnglish (US)
Pages (from-to)1404-1410
Number of pages7
JournalJournal of Organic Chemistry
Volume35
Issue number5
StatePublished - 1970

Fingerprint

Bufanolides
Acetals
Benzene
Lactones
Cardenolides
Acetylation
Ketones
Isomers
Methanol
4-toluenesulfonic acid
Heating
Degradation
Water

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Pettit, G., Kasturi, T. R., Knight, J. C., & Occolowitz, J. (1970). Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements. Journal of Organic Chemistry, 35(5), 1404-1410.

Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements. / Pettit, George; Kasturi, T. R.; Knight, John C.; Occolowitz, John.

In: Journal of Organic Chemistry, Vol. 35, No. 5, 1970, p. 1404-1410.

Research output: Contribution to journalArticle

Pettit, G, Kasturi, TR, Knight, JC & Occolowitz, J 1970, 'Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements', Journal of Organic Chemistry, vol. 35, no. 5, pp. 1404-1410.
Pettit G, Kasturi TR, Knight JC, Occolowitz J. Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements. Journal of Organic Chemistry. 1970;35(5):1404-1410.
Pettit, George ; Kasturi, T. R. ; Knight, John C. ; Occolowitz, John. / Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements. In: Journal of Organic Chemistry. 1970 ; Vol. 35, No. 5. pp. 1404-1410.
@article{4a6384eaa2404c03b1fbaeae13e1e547,
title = "Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements",
abstract = "Several methods were developed for converting isodigitoxigenin (2a) into methyl acetals 4b and 4c. Of these, methanolysis (followed by acetylation) of isodigitoxigenin in the presence of p-toluenesulfonic acid proved most useful. Each isomer reached an equilibrium corresponding to ca. 3:1 acetal 4c to 4b within 15 min in benzene containing p-toluenesulfonic acid. Addition of dihydropyran to the equilibrium mixture resulted in excellent conversion into vinyl ether 5a. Heating either acetal 4b or 4c in benzene containing p-toluenesulfonic acid led to a skeletal rearrangement culminating in formation of C-norcardenolide 6. In addition to results of physical measurements, the structure of spiran 6 was confirmed by degradation to methyl ketone 8. Similar rearrangement of isodigitoxigenin gave spiran 9 accompanied by C-norcardenolide 6. Treating lactone 9 with p-toluenesulfonic acid in methanol-water provided acetals 10a and 10b, which on further contact with p-toluenesulfonic acid in refluxing benzene gave lactone 9 and cardenolide 6. Evidence underlying the stereochemical assignments noted for structures 4, 9, and 10 was also discussed.",
author = "George Pettit and Kasturi, {T. R.} and Knight, {John C.} and John Occolowitz",
year = "1970",
language = "English (US)",
volume = "35",
pages = "1404--1410",
journal = "Journal of Organic Chemistry",
issn = "0022-3263",
publisher = "American Chemical Society",
number = "5",

}

TY - JOUR

T1 - Bufadienolides. 8. 12(13→14)abeo skeletal rearrangements

AU - Pettit, George

AU - Kasturi, T. R.

AU - Knight, John C.

AU - Occolowitz, John

PY - 1970

Y1 - 1970

N2 - Several methods were developed for converting isodigitoxigenin (2a) into methyl acetals 4b and 4c. Of these, methanolysis (followed by acetylation) of isodigitoxigenin in the presence of p-toluenesulfonic acid proved most useful. Each isomer reached an equilibrium corresponding to ca. 3:1 acetal 4c to 4b within 15 min in benzene containing p-toluenesulfonic acid. Addition of dihydropyran to the equilibrium mixture resulted in excellent conversion into vinyl ether 5a. Heating either acetal 4b or 4c in benzene containing p-toluenesulfonic acid led to a skeletal rearrangement culminating in formation of C-norcardenolide 6. In addition to results of physical measurements, the structure of spiran 6 was confirmed by degradation to methyl ketone 8. Similar rearrangement of isodigitoxigenin gave spiran 9 accompanied by C-norcardenolide 6. Treating lactone 9 with p-toluenesulfonic acid in methanol-water provided acetals 10a and 10b, which on further contact with p-toluenesulfonic acid in refluxing benzene gave lactone 9 and cardenolide 6. Evidence underlying the stereochemical assignments noted for structures 4, 9, and 10 was also discussed.

AB - Several methods were developed for converting isodigitoxigenin (2a) into methyl acetals 4b and 4c. Of these, methanolysis (followed by acetylation) of isodigitoxigenin in the presence of p-toluenesulfonic acid proved most useful. Each isomer reached an equilibrium corresponding to ca. 3:1 acetal 4c to 4b within 15 min in benzene containing p-toluenesulfonic acid. Addition of dihydropyran to the equilibrium mixture resulted in excellent conversion into vinyl ether 5a. Heating either acetal 4b or 4c in benzene containing p-toluenesulfonic acid led to a skeletal rearrangement culminating in formation of C-norcardenolide 6. In addition to results of physical measurements, the structure of spiran 6 was confirmed by degradation to methyl ketone 8. Similar rearrangement of isodigitoxigenin gave spiran 9 accompanied by C-norcardenolide 6. Treating lactone 9 with p-toluenesulfonic acid in methanol-water provided acetals 10a and 10b, which on further contact with p-toluenesulfonic acid in refluxing benzene gave lactone 9 and cardenolide 6. Evidence underlying the stereochemical assignments noted for structures 4, 9, and 10 was also discussed.

UR - http://www.scopus.com/inward/record.url?scp=0014780238&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0014780238&partnerID=8YFLogxK

M3 - Article

VL - 35

SP - 1404

EP - 1410

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

SN - 0022-3263

IS - 5

ER -