Hiroshi Takayanagi

Oxidative cleavage reactions of catechol and phenol to monoester of cis,cis,-muconic acid with the oxidizing systems of O2/CuCl, KOH/CuCl2

Abstract Oxidative cleavage reactions of catechol with CuCI to give monoester of cis,cis -muconic acid in pyridine containing alcohol was investigated under various conditions. The same oxidation was carried out also with the systems of KO 2 /CuCl 2 and KOH/CuCl 2 in pyridine containing alcohol in the absence of oxygen. Phenol was oxidized with the same oxidizing systems to give the same monoester of muconic acid.

Facile oxidative conversion of hydrazides of carboxylic acids to corresponding acids, esters and amides using copper compounds

Oxidative conversion of hydrazides of carboxylic acids to acids, esters and amides using Cu salts was studied. Acids were obtained in high yields by using a catalytic amount of Cu(OAc)2 at room temperature by bubbling oxygen. Hydrazides were converted to esters by the treatment with Cu(OR)Cl or Cu(OR)2 formed in situ from CuCl2 and sodium alkoxide. Amides were obtained in high yields by the oxidation of hydrazides with CuCl2 in the presence of amines.

Efficient copper-catalyzed oxidation of dihydrazones of α-diketones to disubstituted acetylenes

Abstract Dihydrazones of α-diketones were oxidized by using Cu 2 Cl 2 /O 2 /pyridine system in dichloromethane at room temp to give disubstituted acetylenes. Although the dihydrazones were found to be oxidized with four equivalents of Cu(II) salt without oxygen, efficient oxidation of the dihydrazones proceeded smoothly in the presence of a catalytic amount of Cu(I) chloride under oxygen, thus providing a convenient preparative method of distributed acetylenes.