- The Preparation and Photoreaction of Spiro2,7>octen>-8'-ones. An Intramolecular Cycloaddition of Photochemically Generated Ketene with the Epoxide Ring
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The oxidations of 1,5-dimethyl- and 1,3,5-trimethyl-6-methylenetricyclo2,7>oct-3-en-8-ones with 3-chloroperbenzoic acid or thallium(III) acetate resulted in the formation of 1',5'-dimethyl and 1',3',5'-trimethylspiro2,7>octen>-8'-ones (2a and 2b).The oxidation occured stereoselectively on the exocyclic double bond from the exo-side.The photochemical reactions of 2a and 2b resulted in the formation of 4,8-dimethyl and 4,6,8-trimethyl-3,4-dihydro-1H-2-benzopyran-3-ones, both of which would be derived from an ene-type reaction of the ketene intermediate with the epoxide ring involved in the electronic system.The intermediacy of the ketene was assessed by low-temperature infrared spectrosopy as well as by a trapping experiment, the mechanistic pathways were confirmed by conducting the photoreaction in deutereted methanol.
- Nitta, Makoto,Omata, Akihiko,Nakatani, Hazime
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p. 2009 - 2012
(2007/10/02)
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