1: diethyl ((methylsulfonyl)methyl)phosphonate With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 0.5 h; 2: 3-(2,5-dioxo-pyrrolidin-1-yl)propionaldehyde in tetrahydrofuran; hexane T=-78 - 20°C;

Lawesson's reagent in toluene Heating;