Acyl Cyanide. V. The Synthesis of 1-Cyano-1-alkenyl Esters by the Reaction of Acyl Cyanides with Acid Anhydrides and Isocyanates

The reactions of enolizable acyl cyanides (acetyl, propionyl, and isobutyryl cyanide) with acid anhydrides (acetic, propionic, butyric, isobutyric, and benzoic anhydride) in the presence of a catalytic amount of tertiary amines (pyridine, lutidines, 4-(dimethylamino)pyridine) produced the corresponding 1-cyano-1-alkenyl carboxylates. In the reactions of propionyl cyanide, (Z)-1-cyano-1-propenyl carboxylates were formed predominantly over the (E)-isomers (isomer ratios Z⁄E were ca. 80/20). The reactions of the cyanides with isocyanates also gave the corresponding 1-cyano-1-alkenyl carbamates in moderate yields, and the acid-treatments of 1-cyano-2-methyl-1-propenyl phenylcarbamate induced its annelation into 3-phenyl-1,3-oxazolidine-2,4-dione derivatives.