To a solution off 7-cyclohexyl-3,4-dihydronaphthalene-2-carboxylic acid (0.51 g) in N,N-dimethylformamide (DMF) (15 ml), diethyl phosphorocyanidate (DEPC) (0.36 g) was added under ice-cooling conditions, followed by stirring for 30 minutes. Diethyl 4-aminobenzylphosphonate (0.54 g) and triethylamine (0.22 g) were then added in this order, followed by stirring under ice-cooling conditions for 2 hours, after which the reaction mixture was poured into water and extracted with ethyl acetate. The ethyl acetate layer was washed with water and brine, and dried (MgSO4), after which the solvent was evaporated off. The residue was subjected to silica gel column chromatography and eluted with ethyl acetate-hexane (1:2, v/v) to yield 7-cyclohexyl-N-(4-diethoxyphosphorylmethylphenyl)-3,4-dihydronaphthalene-2-carboxamide (0.43 g, 45%) as colorless prisms having a melting point of 137°-138° C.
