Acyl Cyanide. VI. The Synthesis of 1-Cyano-1-alkenyl Esters by the Reaction of Acyl Cyanides with Acid Chlorides. Synthesis and Mechanism

The reactions of enolizable acyl cyanides (acetyl, propionyl, isobutyryl, and diphenylacetyl cyanide) with acid chlorides (acetyl, propionyl, benzoyl, p-nitrobenzoyl, diphenylcarbamoyl, and dimethylcarbamoyl chloride) in the presence of tertiary amines gave the corresponding 1-cyano-l-alkenyl carboxylates or carbamates in good yields. Among several solvents and amines examined in the reaction of acetyl cyanide with propionyl chloride, benzene and pyridine seem to be most appropriate. The maximum yield (98%) of the ester was attained in benzene when both the chloride and pyridine were used in excess amounts (1.2–1.4 times the amount of the cyanide). The rate of reaction depended little on the concentration of the chloride but on both the cyanide and the amine being of first order in each reactant; it was also influenced by the basicity of tertiary amines and, in the case of weak bases, additionally by their nucleophilic power.