Control of stereochemistry in an intramolecular Diels–Alder reaction by the phenylsulfonyl group; an improved synthesis of pisiferol
- 1 January 1997
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 23,p. 3531-3536
- https://doi.org/10.1039/a702761c
Abstract
Thermolysis of 4a (X = H) gives 6a and 6b (X = H) in a ratio of 1∶4 whereas 4b (X = SO2Ph) gives more of the trans-ring junction product 6a (X = SO2Ph) suitable for the synthesis of pisiferol [ratio 6a∶6b (X = SO2Ph) = 1.5∶1]. Base catalysed elimination of the phenylsulfonyl group from 6a (X = SO2Ph) gives 18 which is hydrogenated to 6a (X = H), an intermediate in the synthesis of pisiferol. Both 6a and 6b (X = SO2Ph) have ring B in a half-boat conformation.Keywords
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