Abstract In previous papers2–6) we have reported the copper catalyzed reactions of isonitrile with various RQH compounds, in which the terminal carbon atom of isonitrile is inserted between heteroatom-hydrogen bonds, ie, NH bond of amine, PH of phosphine, OH of alcohol, SH of thiol and Si-H of silane,(eq. 1). In these reactions, the derivatives of hypothetical “fonirnidfc acid”, HC ([dbnd] NR) OH, are produced in high yields. These ...