Cyclooctanone 5- hydroxy

The intramolecular cyclization dominates other possible reactions even in solvents highly susceptible to free radical attack (110). Thus, irradiation of 4,5-octanedione in butanal gives 2-hydroxy-3-methyl-2-propylcyclobutanone in 92% yield (110). Irradiation of 1,2-cyclo-decanedione (Formula 264) gives 1-hydroxybicyclo [6.2.0 ]decan-10-one (Formula 265) in 74% yield and cyclooctanone (Formula 266) in 9% yield (111). The cyclooctanone is produced together with ketene by a secondary photolysis of Formula 265 (111). 

Reaction of c/5-l,2-cyclooctanediol with dichlorocarbene yields cyclooctanone, cyclooctene, and the dichlorocarbene adduct of cyclooctene according to equation 3.6 [10]. The formation of cyclooctanone is expected from a pinacol rearrangement of the a-hydroxy carbonium ion formed by decomposition of the a-hydroxyalkoxy-chlorocarbene adduct. On the other hand, reaction of the alkoxychlorocarbene with an adjacent alkoxide anion yields a cyclic dialkoxycarbene which decomposes with loss of carbon dioxide and formation of cyclooctene. Addition of dichlorocarbene to cyclooctene yields 2,2-dichlorobicyclo[8.1.0]-nonane. 

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