1: dimethyl methoxycarbonylmethanephosphonate With sodium hydride in N,N-dimethyl-formamide T=20°C; 0.5 h; 2: methyl 3-bromo-propionate in N,N-dimethyl-formamide T=100°C; 16 h; Further stages.;

potassium carbonate in N,N-dimethyl-formamide T=100°C; 6 h;