Abstract By treatment with bases in methanolic solution N-substituted N-nitroso-amino- acetonitriles (I) undergo an internal rearrangement of the nitroso group to yield α-isonitroso- aminoacetonitriles (II). The structures of the rearrangement products are proved by their physico-chemical properties, by chemical degradation to known products, and by transformation into a number of derivatives. Similar compounds in which the nitrile group ...