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Intramolecular photocycloaddition of olefin-tethered benzo[a]spiro[2,5]octa-1,4-dien-3-one derivatives
β Scribed by Xuqing Zhang; Arthur G. Schultz
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- French
- Weight
- 77 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0040-4039
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β¦ Synopsis
Photolysis of benzo[a]spiro [2,5]octa-1,4-dien-3-one derivative 8a afforded spiro-fused tetracycles 10 as a pair of diastereomers in 1.7:1 ratio. The photochemical process occurred by cycloaddition of the intermediate-sulfone stabilized biradical 9 to the tethered olefin. Photolysis of dienone 8b gave only spiro-fused tetracycle 11 without bridged adduct 12.
π SIMILAR VOLUMES
Irradiation of 2,4-cyclohexadienones (L) usually produces ketenes. Most commonly, these ketenes either thermally recyclize to dienone or, in the presence of nucleophiles, react to form open-chain unsaturated acids or their derivatives.lm4 In special cases, however, the ketene may thermally cyclize t