Expeditious syntheses of (±)-5-oxosilphiperfol-6-ene and (±)-silphiperfol-6-ene

Organic Letters

Volumn 2, Issue 17, 2000, Pages 2711-2712

  Reddy, T Jagadeeswar ^a   Rawal, Viresh H ^a  

^a UNIVERSITY OF CHICAGO   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

5 OXOSILPHIPERFOL 6 ENE; 5-OXOSILPHIPERFOL-6-ENE; DYES, REAGENTS, INDICATORS, MARKERS AND BUFFERS; OZONE; SESQUITERPENE; SILPHIPERFOL 6 ENE; SILPHIPERFOL-6-ENE;

ARTICLE; CHEMISTRY; CONFORMATION; STEREOISOMERISM; SYNTHESIS;

INDICATORS AND REAGENTS; MOLECULAR CONFORMATION; OZONE; SESQUITERPENES; STEREOISOMERISM;

EID: 0034710512     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol006292q     Document Type: Article

References (27)

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22. Prior to our studies, there were no reports on the use of enone 6 in a Diels-Alder reaction and only two on diene 5. See: (a) Ford, W. T. J. Org. Chem. 1971, 36, 3979-3987.
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24. Previously, this enone was prepared from 3-methylcyclohexanone in seven steps in 21% overall yield. See: Takeda, A.; Shinhama, K.; Tsuboi, S. J. Org. Chem. 1980, 45, 3125-3128.
25. 4. Although the thermal cycloaddition was successful, it proceeded more slowly and with lower selectivity.
26. The product was isolated in 92% yield after chromatography and consisted of a (20:1):(1.4:1.0) ratio of (endo-α:β):(exo-α:β) diastereomers, the major product being the desired endo-α (4). The assigned structures are consistent with 2D NOE experiments. Further chromatographic purification gave the desired isomer contaminated with some exo isomers in 84% yield. This mixture was used in the next step, at which point the exo isomers are consumed through unproductive processes.
27. All compounds discussed exhibited spectral properties consistent with the assigned structures (see Supporting Information). The spectral data for 1 and 2 were identical to those reported for the natural products (refs 3c, 1b,and 4).