Effect of Substituents, Solvent, and Temperature on the Reactivity of the Zwitterionic Peroxides Arising from the Photo-Oxygenation of 2-(Methoxymethylidene)- and 2-(Phenoxymethylidene)adamantane
✍ Scribed by Charles W. Jefford; Hamish G. Grant; Danielle Jaggi; John Boukouvalas; Shigeo Kohmoto
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- German
- Weight
- 511 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
The photo‐oxygenation of 2‐(methoxymethylidene)adamantane (3) creates a zwitterionic peroxide which may be captured by acetaldehyde to give the corresponding pair of diastereoisomeric tricyclo[3.3.1.1^3,7^]decane‐2‐spiro‐6′ ‐(3′ ‐methyl‐5′ ‐methoxyl′, 2′, 4′ ‐trioxanes) (4). Ease of capture depends strongly on solvent polarity and temperature. When these are low, yields of trioxine are high (∼ 80%). Conversely, 1,2‐dioxetane formation is favoured at high temperature and solvent polarity. 2‐(Phenoxymethylidene)adamantane (5), on photo‐oxygenation, only gives the corresponding 1,2‐dioxetene, even in the presence of acetaldehyde. From a Hammett, study of the‐oxygenation of the enol ether 5 and p‐methoxy, p‐methyl, p‐chloro and m‐chloro derivatives, 9, 11, 13, and (15), a good linear relation was found between substituent constants and oxygenation rates which yielded reaction constants (ρ) of 2.59, −2.40, −1.09, and −0.90 in benzene, AcOET, CH~2~Cl~2~, and MeOH respectively. This data to the formation of a zwitterionic peroxide which enjoys stabilization from its won substituents and by competing solvation and further explains the predominance of dioxetane to the detriment of trioxane formation.