Development of New Transition Metal-Catalyzed Systems under Oxygen

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We disclosed a new palladium (II) catalytic system for oxidation of alcohols. The system consisted of a catalytic amount of Pd (OAc)_2, atmospheric pressure of oxygen as an oxidant, and an organic base such as pyridine in toluene. The finding is as follows : 1) a selective oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones, respectively, 2) oxidation of tertiary cyclobutanols to various organic compounds such as β, γ-unsaturated ketones, cyclopentanone derivatives, tetralone derivatives, and cyclopropyl ketones depending on the kind of substituents on the cyclobutane ring. We also developed a new solid catalyst, palladium (II) hydrotalcite, by the reaction of Pd (OAc)_2 with a basic clay hydrotalcite. This solid catalyst is reusable and also has a characteristic feature in oxidation of unsaturated allylic alcohols such as geraniol and nerol to the corresponding aldehydes without any isomerization at the double bond. All these new findings have been reported in scientific journals of Japan, UK and USA.