Development of Novel Synthetic Reaction Using Cycloalkanones

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PGB_1 analogues with functionalized alpha-side chain have been synthesized in several steps from 1,3-cyclopentanedion. Introduction of alpha-and omega-side chains into the PGB_1 cyclopentenone skeltone has been accomplished by replacement reaction via stabilized carbanions. The substitution reaction with stabilized carbanion has been confirmed to process via a radical chain mechanism of S_<RN>1 type by the ESR studies. The PGB_1 thus obtained were subjected to the screening test for the biological activities. Among the PGB_1 synthesized in the present study, it was found that 6 samples of these act as insecticide of tick and rice insect. From the consideration of S_<RN>1 type reaction, it was found that a stable radical intermediate is formed in the course of this reaction.By using this methodology, we are able to confirm a general preparation method of cyclized nitroxy radicals bearing quarternary asymmetric carbon.On the other hand, the synthesis of 2,6-dialkylphenols which is difficult to prepare by conventional method is accomplished from the direct condensation reaction between cyclohexanone and aldehydes catalyzed by zirconocene complexes. The anti-oxidant property of the resulting phenols was compared with those of commercial avairable ones, and these were comparable or superier to comventinal phenol system of anti-oxidants. This method has been extended to the cyclopentenone synthesis from ketones and aldehydes, and esters by Tishchenko rection.