- Ring-D aromatic phytosteroids; a model for biogenesis by way of carbon radical rearrangement
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A mechanism is postulated for the biogenesis of the unique ring-D aromatic phytosteroids from Nicandra physaloides, which involves rearrangement, ring expansion, and aromatisation of a carbon radical generated by cytochrome P450 (Scheme 1). In support, model hydrindene acids 15b and 18b have been synthesized and subjected to homolytic decarboxylation; the latter acid yielded 6-methyltetralin 24, in biomimetic fashion. The isomeric acid afforded not only 6-methyltetralin 24 but also 5-methyltetralin 26; mechanisms for this unusual rearrangement are discussed.
- Green, Stuart P.,Whiting, Donald A.
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p. 1027 - 1034
(2007/10/03)
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- Stereoselective Synthesis of (cis-Hydrindane) Models for C-18 Radical Reactivity in Steroid C/D Rings
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The keto-acid 5 undergoes stereospecific Peterson reaction to afford the (Z)-α-unsaturated ester-acid 6, and the derived phenyl selenoester cyclises also stereospecifically to the cis-hydrindanone 8 via a 5-exo acyl radical process; the ketone 8 is transformed through enone 11 into the diene-acids 2 and 3, models for study of C-18 radical reactions in steroid C/D systems.
- Green, Stuart P.,Whiting, Donald A.
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p. 1753 - 1754
(2007/10/02)
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