To (R)—N—((R)-(4-bromophenyl)(phenyl)methyl)-2-methylpropane-2-sulfinamide, 23-a, (16 g, 43.83 mmol), ethyl methylphosphite (9.47 g, 87.67 mmol) and Et3N (13.3 g, 132 mmol) in THF (200 ml) was added PdCl2(dppf) (1.6 g). 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 dichloromethane and washed with brine. The organic layer was concentrated under vacuum and the residue was purified over silica gel (petroleum ether:ethyl acetate=1 l/1) to provide the crude product, 23-b, (9.5 g, 55%).
