Steroidal Cyclic Ketals. XV.<sup>1,2</sup> 17,21-Oxido-steroids. Part I. Preparation

Allen, William S.; Bernstein, Seymour; Heller, Milton; Littell, Ruddy

doi:10.1021/ja01623a028

Cited by 15 publications

(10 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Starting from the 12,13-epoxy-trichothecancs roridin C (trichodermol) (l), verrucarol (15) and trichothccolone (25), the isomeric 2~,13-epoxp-apotrichothecancs 9, 20 and 33 have been synthcsized. I n these compounds the oxetanc group proved t o be unexpectedly stable to mincral acids and complex metal hydrides, probably due t o its fusion t o a cyclopentanc ring.…”

mentioning

confidence: 99%

2β, 13‐Oxido‐apotrichothecane: Synthese, chemische und physikalische Eigenschaften. Verrucarine und Roridine, 23. Mitteilung

Schumacher

Gutzwiller

Tamm

1971

Helvetica Chimica Acta

View full text Add to dashboard Cite

355,260) Bcr. C 47,33 H 3,97 N 3,9404 Gcf. C 47,34 H 4,23 N 3,81% Finanziclle Unterstiitzung verttanltcn wir den1 Schweiz. Nationutfonds. LITERATURVERZETCHNI S 111 (13. WIT. 71)S'ummuvy. Starting from the 12,13-epoxy-trichothecancs roridin C (trichodermol) (l), verrucarol (15) and trichothccolone (25), the isomeric 2~,13-epoxp-apotrichothecancs 9, 20 and 33 have been synthcsized. I n these compounds the oxetanc group proved t o be unexpectedly stable to mincral acids and complex metal hydrides, probably due t o its fusion t o a cyclopentanc ring. Thc I R . and NMR. spectra of the oxetanes are discussed.

show abstract

mentioning

confidence: 99%

2β, 13‐Oxido‐apotrichothecane: Synthese, chemische und physikalische Eigenschaften. Verrucarine und Roridine, 23. Mitteilung

Schumacher

Gutzwiller

Tamm

1971

Helvetica Chimica Acta

View full text Add to dashboard Cite

show abstract

“…A similar argument may be applied to the dissolving metal reductions of 11-keto steroids which afford the lla-ols. 26 sodium borohydride reduces the ketone extremely slowly to give the highly hindered axial ll/3-ol. In terms of the above mechanism for metal-ammonia reductions, the rate of protonation of the radical anion would be greatly suppressed, either due to steric hindrance, or more probably to a dramatic increase in activation energy for protonation due to the incipient axial-axial interactions with C-18 and C-19 in the transition state.…”

Section: Discussionmentioning

confidence: 99%

The metal-ammonia reduction of ketones

Huffman¹,

Charles²

1968

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The reductions of a series of cyclohexanones, norbornanone, and camphor by alkali metals in liquid ammonia have been carried out. The reductions of the cyclohexanones afford a distribution of products corresponding to nearly exclusive formation of the equatorial alcohol based on the ground-state conformer population of the ketone. Norcamphor gives 68-91 % of the thermodynamically less stable ewfo-norborneol, depending on the conditions of the reduction, while camphor affords nearly an equilibrium mixture of borneol and isoborneol. A reaction path consistent with these data is suggested. Following Barton's classical papers which laid the foundations for that area of organic chemistry known as conformational analysis,3 it has been widely accepted that dissolving metal reductions of saturated cyclic ketones give rise to either exclusively the thermodynamically stable alcohol or to mixtures in which this isomer predominates.3•4 In spite of several cases (1) This work was supported in part by Career Development Award K3-GM-5433 from the National Institutes of Health.(2) NASA Fellow, 1964-1967 (3) (a) D.

show abstract

“…Presumably, the acetyl groups undergo hydrolytic cleavage more readily than benzoyl groups in the presence of strong base as has been observed in the Japp-Klingemann type of reaction. [4][5][6][7] The isolations in this work of l,5-diphenyl-3benzoylformazan (VIII) from the coupling of 1-phenyl-1.3-butanedione (II) and of 1-phenyl-1,2,3-butanetrione 2-phenylhydrazone provide additional evidence that the benzoyl group undergoes cleavage less readily than the acetyl group. However, the benzoyl group will also cleave at about 50°in the presence of an acid or a base and l,5-diphenyl-3-benzoylformazan is formed from the di(phenylazo) compound IX.…”

Section: -154°mentioning

confidence: 99%