1: With 1-propanephosphonic acid cyclic anhydride; triethylamine in ethyl acetate; acetonitrile T=20°C; 0.5 h; 2: With hydroxylamine hydroxide in ethyl acetate; acetonitrile T=20°C;

hydroxylamine hydrochloride; sodium methylate

hydroxylamine hydrochloride; sodium ethanolate

lithium aluminium tetrahydride in tetrahydrofuran Heating;