Organocatalytic Cleavage of Fatty 1,2-Diketones to Esters

International audienceThe cleavage of a fatty 1,2-diketone derivedfrom methyl oleate into the corresponding esters, i.e., methylnonanoate and dimethyl azelate, was studied by organo-catalysis using oxygen as a clean oxidant. Only carbenegenerated from thiazolium salts and K2CO3could efficientlycatalyze this transformation. It was found that, under theoptimized conditions, the oxidative cleavage leads to theformation of a 1:1 mixture of esters and potassiumcarboxylates. An acidic treatment of the mixture, followedby esterification with methanol, led to the desired esters with75 and 77% yield. This protocol was extended to a range ofsymmetrical and unsymmetrical fatty 1,2-diketones and the corresponding esters were isolated with 61−84% yiel