To (R)—N—((R)-(4-bromophenyl)(2,4-difluorophenyl)methyl)-2-methylpropane-2-sulfinamide, 20-c, (1 g, 2.5 mmol), ethyl methylphosphite (0.54 g, 5 mmol) and Et3N (0.63 g, 6.25 mmol) in THF (10 ml) was added PdCl2(dppf) (183 mg). The mixture was allowed to stir overnight at reflux. The mixture was filtered and the filtrate was concentrated under vacuum. The residue was taken into ethyl acetate and washed with brine. The organic layer was concentrated under vacuum and the residue was purified over silica gel to give compound, 20-d, (dichloromethane:methanol=50/1) to provide the product (866 mg, 81%).
