The course of the reaction between phosphorus trichloride, acetamide, and ethyl oxoalkanecarboxylates was studied in terms of the production of side-products. When alkyl 2- oxocycloalkanecarboxylates were used as substrates, together with the expected products— 2-amino-2-phosphonocycloalkanecarboxylic acids—three side-products, namely 1- aminocycloalkanephosphonic acids (decarboxylation products of the latter compounds), 1 ...