JPH0254814B

PURPOSE:To produce the titled compound useful as a synthetic raw material of brevicomin known as an insect pheromone, easily in high yield, by oxidizing a cycloolefin compound under light radiation in the presence of ferric chloride without separating the reaction intermediate. CONSTITUTION:The cycloolefin compound of formula I (R is methyl; R is methyl or ethyl; n is 1 or 3) is used as a raw material, and is irradiated with light transmitted through a Pyrex glass in the presence of ferric chloride for preferably >=4hr to obtain the alpha-chlorodiketone compound of formula II. The product can be applied widely in organic syntheses by the selective conversion of the alpha-chloroketone group. For example, 1-ethyl-6-methyl-1-hexene of formula IIIis irradiated with light transmitted through Pyrex glass in the presence of ferric chloride under the above reaction conditions to obtain the compound of formula IV, which is subjected to the reduction, epoxidization and acid treatment to obtain a compound known as an insect pheromone.