Various alpha-cyano carbonates are taught in the literature. Cyanophenylmethyl ethyl ester of carbonic acid and the method of preparing such is taught by Uff et al. in "Formation of Cyanohydrin Carbonates of Aromatic Aldehydes and Aryl Heteroaryl Ketones", Synthetic Communications, 8 (3), 163-167 (1978).
USPTO Backgrounds
USPTO Backgrounds