Trimethylsilyldiazomethane in the preparation of diazoketones via mixed anhydride and coupling reagent methods: a new approach to the Arndt–Eistert synthesis

Reaction of trimethylsilyldiazomethane with a mixed anhydride derived from a carboxylic acid by the action of ethyl chloroformate, yields the corresponding diazoketone in high yield. Subsequent Wolff rearrangement of the diazoketone leads to the homologated ester. Reaction of trimethylsilyldiazomethane with carboxylic acid–dicyclohexylcarbodiimide mixtures leads to the formation of diazoketone and trimethylsilylmethyl ester in equimolar ratio via an acid anhydride intermediate. The N-hydroxysuccinimide ester of the acid does not react with trimethylsilyldiazomethane or with its more reactive lithiated derivative.