Synthese, spektroskopische und konformationelle Untersuchungen von 10α‐Methyl‐Steroid‐Spirolactonen

Nickisch, Klaus; Bittler, D.; Cleve, Gerhard; Eckle, Emil; Laurent, Henry

doi:10.1002/jlac.198819880614

Cited by 2 publications

(3 citation statements)

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“…This approach starts with the migration of the double bond of the enone cis-4 to the B ring and concomitant protection of the carbonyl at C-3 to give alkene 38 in 51% (nonoptimized) yield. 25 The stereoselective epoxidation of the double bond is carried out in high yield by using Yang's protocol. 26 In the absence of the chelating hydroxyl at C-3, the epoxide 39 opened selectively at the secondary center to afford the desired diol 40, exclusively.…”

Section: Resultsmentioning

confidence: 99%

“…We therefore undertook a new pathway to the AB ring system (Scheme 17). This approach starts with the migration of the double bond of the enone cis - 4 to the B ring and concomitant protection of the carbonyl at C-3 to give alkene 38 in 51% (nonoptimized) yield .…”

Section: Resultsmentioning

confidence: 99%

“…1 H NMR (CDCl3, 500 MHz) δ 8. 25 (()-(1S,2R,4R,4aR,8aR) Methyl 2-Benzoyloxy-4-(dimethylphenylsilyl)decahydronaphth[1,8a-b]oxirene-4a-carboxylate (35). The alcohol 3 (140 mg, 0.39 mmol) was dissolved in THF (6 mL) and treated with triphenylphosphine (204 mg, 0.77 mmol) and benzoic acid (95 mg, 0.77 mmol) at ambient temperature.…”

Section: (()-(1s2s4r4ar8ar) Methyl 2-hydroxy-4-(dimethylphenylsilyl)d...mentioning

confidence: 99%

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Synthetic Approach to the AB Ring System of Ouabain

Jung

Piizzi

2003

J. Org. Chem.

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Several novel hydroxylated cis-decalin derivatives, potential intermediates for the synthesis of the AB ring system of the important cardiotonic steroid ouabain, have been synthesized from commercially available starting materials. The first step in the preparation of these highly functionalized intermediates is a Robinson annulation of the beta-keto ester 6 and the 4-silyl-3-buten-2-one 5 to furnish the octalone 4 with good diastereoselectivity in fair yield (due to competition with a novel silicon-to-carbon phenyl migration). Reduction of the epoxy alcohol 3 (derived from 4 in two high-yielding steps) with LiAlH(4) gave a mixture of the desired triol 11 along with the product of an unusual reductive opening at the tertiary carbon, namely the triol 12. A plausible mechanism for this unusual reduction is presented as are possible methods for avoiding it. In particular, reduction of the corrresponding epoxy ketone 15 with aluminum amalgam proceeded in good yield to give the hydroxy ketone 16. Also reduction of the epoxide ester having the inverted stereochemistry at C3 afforded the desired tertiary alcohol 33 in good yield. Another approach using the beta,gamma-unsaturated ketal 38 permitted the formation of the tertiary alcohol 40. Fleming oxidation of the related, very functionalized silane 39 afforded the desired 1beta-alcohol 41 in fair yield. Finally a novel rearrangement was observed when the epoxy alcohol 24 was treated with DIBAL to effect loss of the angular hydroxymethyl group to produce the tetrasubstitued alkene 29 in high yield.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: (()-(1s2s4r4ar8ar) Methyl 2-hydroxy-4-(dimethylphenylsilyl)d...mentioning

confidence: 99%

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Synthetic Approach to the AB Ring System of Ouabain

Jung

Piizzi

2003

J. Org. Chem.

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ChemInform Abstract: Synthesis, Spectroscopic and Conformational Investigations of 10α‐Methyl Steroid Spirolactones.

Nickisch¹,

Bittler²,

Cleve³

et al. 1988

ChemInform

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ChemInform Abstract Starting from the mixtures of the ketones (I), the spirolactone-dienone (VII) is prepared according to known procedures. This dienone (VII), on reaction with MeSH (VIII) affords a separable mixture of the isomeric 7-α-methylthio derivatives (IX) and (X), the latter being the thermodynamically more stable isomer. In order to obtain information about the structure-activity relation, the conformations of the rings A and B of the compounds (VI), (VII), (IX) and (X) are determined by CD spectrometry. The results are compared to the energetically preferred conformations calculated by semiempirical quantum mechanical calculations. The methylthio derivatives (IX) and (X) show no aldosterone antagonistic activity in in vivo and in vitro tests.

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Synthese, spektroskopische und konformationelle Untersuchungen von 10α‐Methyl‐Steroid‐Spirolactonen

Cited by 2 publications

References 14 publications

Synthetic Approach to the AB Ring System of Ouabain

Synthetic Approach to the AB Ring System of Ouabain

ChemInform Abstract: Synthesis, Spectroscopic and Conformational Investigations of 10α‐Methyl Steroid Spirolactones.

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