Enantioselective synthesis of both (+)- and (−)-derivatives of bicyclo[4.3.0]nonan-8-one and -3,8-diones from R-carvone

Srikrishna, A.; Reddy, T. Jagadeeswar; Nagaraju, S.

doi:10.1016/0040-4039(96)00106-2

Cited by 16 publications

(15 citation statements)

References 9 publications

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“…The chemical shifts (δ ppm) and the coupling constants (Hz) are reported in the standard fashion with reference to either internal tetramethylsilane (for 1 H) or the central line (77.1 ppm) of CDCl 3 (for 13 C). In the 13 C NMR spectra off-resonance multiplicities, when recorded are given in parentheses. Low and High resolution mass measurements were carried out using a Jeol JMS-DX 303 GC-MS instrument using a direct inlet mode.…”

Section: Methodsmentioning

confidence: 99%

“…1 H (90, 200 and 270 MHz) and 13 C NMR (22.5, 50 and 100 MHz) spectra were recorded on Jeol FX90Q, Brucker ACF-200, WH-270 and AMX-400 spectrometers. The chemical shifts (δ ppm) and the coupling constants (Hz) are reported in the standard fashion with reference to either internal tetramethylsilane (for 1 H) or the central line (77.1 ppm) of CDCl 3 (for 13 C).…”

Section: Methodsmentioning

confidence: 99%

“…Ozonolysis of the isopropylidene group in 20 in methanol-methylene chloride followed by reductive work up with triphenylphosphine furnished the dione (-)-21 in 88% yield, whose structure was established from its spectral data. The molecular ion at m/z 180 in the mass spectrum, presence of two carbonyl absorption bands at 1740 and 1710 cm -1 due to the 5-and 6-membered cyclic ketones, respectively, in the IR spectrum and absence of resonances due to the olefinic carbons in the 13 C NMR spectrum revealed the formation of the dione 21. In the 1 H NMR spectrum, presence of a singlet at δ1.21 and a doublet at 0.9 due to tertiary and secondary methyl groups, respectively, and the 11 lines 13 C NMR spectrum with diagnostic resonances at δ 215.9 and 210.4 due to carbonyl carbons of five and six membered cyclic ketones, respectively, at 40.7 due to the quaternary carbon, at 18.7 and 16.6 ppm due to two methyl groups confirmed the structure of the dione 21.…”

mentioning

confidence: 99%

“…The molecular ion at m/z 180 in the mass spectrum, presence of two carbonyl absorption bands at 1740 and 1710 cm -1 due to the 5-and 6-membered cyclic ketones, respectively, in the IR spectrum and absence of resonances due to the olefinic carbons in the 13 C NMR spectrum revealed the formation of the dione 21. In the 1 H NMR spectrum, presence of a singlet at δ1.21 and a doublet at 0.9 due to tertiary and secondary methyl groups, respectively, and the 11 lines 13 C NMR spectrum with diagnostic resonances at δ 215.9 and 210.4 due to carbonyl carbons of five and six membered cyclic ketones, respectively, at 40.7 due to the quaternary carbon, at 18.7 and 16.6 ppm due to two methyl groups confirmed the structure of the dione 21. Regioselective protection of the 6membered ring ketone with ethylene glycol and a catalytic amount of p-toluenesulfonic acid (pTSA) in refluxing benzene using a Dean-Stark water separator transformed the dione 21 into the (-)-ketoketal 13 in 65% yield, the key intermediate in the sequence, whose structure was established from its spectral data.…”

mentioning

confidence: 99%

“…The structures were confirmed by comparison of the spectral data with the other two diastereomers of the dione. 13 Intramolecular aldol condensation of the dione 17a using 10% aqueous potassium hydroxide in methanol cleanly furnished the enone 18. For the conversion of the isopropenyl moiety into an acetoxy group, regioselective ozonation followed by Craigee rearrangement of the enone 18 was briefly explored.…”

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confidence: 99%

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Enantiospecific formal total synthesis of homogynolide-A

Srikrishna¹,

Reddy²

2001

Arkivoc

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Formal total synthesis of both enantiomers of homogynolide-A, a sesquiterpene containing an α-spiro-β-methylene-γ-butyrolactone moiety fused to a bicyclo[4.3.0]nonane framework, is described. Thus, (R)-carvone was converted into both enantiomers of 3-methylcarvone 14. A reductive allylation, Wacker oxidation and intramolecular aldol condensation sequence transformed 3-methylcarvone into the hydrindanone 18. Regiospecific reduction of the enone followed by a three step degradation of the isopropenyl group converted the hydrindanone 18 into the dione 21, which on regioselective ketalisation furnished the key intermediate ketoketal 13. Methoxymethylene Wittig reaction followed by bromoacetalisation reaction transformed the ketoketal 13 into the bromoacetal 23. The 5-exo-dig radical cyclisation of the bromoacetal 23 followed by the hydrolysis and oxidation of the resultant spiroacetal 24 furnished a 1:4 mixture of the Greene's precursor ketospirolactone 12 and its spiroepimer 26.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Enantiospecific formal total synthesis of homogynolide-A

Srikrishna¹,

Reddy²

2001

Arkivoc

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Wacker Oxidation, The

2014

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Terminal alkene substrates can be converted to methyl ketone products via a palladium‐catalyzed process known as the Wacker oxidation. This process has found widespread application in targeted synthesis, since alkene substrates are easily accessed and unreactive under diverse reaction conditions substrates and the resultant carbonyl products are common precursors for diverse synthetic manipulations. This chapter covers the application of the Wacker oxidation and variations of the Wacker oxidation to various types of alkene substrates. The literature covered spans the inception of the reaction in 1959 through November 2012. A discussion of the current mechanistic understanding is presented, emphasizing considerations that are relevant to synthetic application, including how the nature of the alkene substrate and nucleophiles other than water are proposed to influence the mechanistic pathways and ultimately the product distribution. The “Scope and Limitations” section is separated into discussions relating to functional group tolerance, the influence of heteroatoms proximal to the alkene substrate, and Wacker‐type oxidations that do not result in carbonyl products, such as cyclization reactions and aza‐Wacker reactions. Select applications of the Wacker oxidation in total synthesis are presented, as well as a comparison to other methods and examples of experimental conditions.

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Cyclopentanes

2015

Cyclopropanes in Organic Synthesis

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Enantioselective synthesis of both (+)- and (−)-derivatives of bicyclo[4.3.0]nonan-8-one and -3,8-diones from R-carvone

Cited by 16 publications

References 9 publications

Enantiospecific formal total synthesis of homogynolide-A

Enantiospecific formal total synthesis of homogynolide-A

Wacker Oxidation, The

Cyclopentanes

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