Diazoketones from the interaction of diazoalkanes with carboxylic acid–dicyclohexylcarbodi-imide mixtures

Abstract

The addition of a mixture of a carboxylic acid (1 mol.) and dicyclohexylcarbodi-imide (1 mol.) in ether to diazomethane (1·25 mol.) or diazoethane (1·25 mol.) provides the corresponding diazo-ketone (ca. 0·5 mol.) through an acid anhydride intermediate. This procedure is useful for the preparation of diazo-ketones which cannot be prepared by conventional procedures from the acid chloride; e.g., attempts to prepare 3-cyanopropionyl chloride have been unsuccessful but the addition of diazomethane to a mixture of 3-cyanopropionic acid and dicyclohexylcarbodi-imide gave 4-diazo-3-oxobutane-1-carbonitrile in ca. 30% yield.