Benzyloxyureas (4) have been prepared by reactions of diethyl 3-benzyloxyamino-propyl-phosphonate (3) with isocyanates, potassium cyanate or 1,1’-carbonyldiimidazole / methylamine. Conversion of phosphonic esters 4 into phosphonic acids 6 by means of bromotrimethylsilane and catalytic hydrogenation of 4, 6 afforded the target compounds 5, 7.