A mixture of 5-[3-(4-bromo-phenyl)-3-o-tolyl-propionyl]-1-methyl-1H-pyridin-2-one (150 mg, example 162, step 3), dichloro(1,1′-bis(diphenylphosphino)ferrocene)palladium(II) dichloromethane adduct (30 mg), NaHCO3 (77 mg), ethyl acetate (4.5 ml) and water (1.5 ml) was treated with carbon monoxide at 150° C./80 bar for 20 h. After cooling to room temperature, the mixture was filtered. The filter cake was washed with ethyl acetate and with aqueous KHSO4 solution. The combined filtrate was extracted with ethyl acetate. The organic phase was washed with brine, dried (MgSO4), filtered and concentrated to dryness. The residue was taken up in 1 M aqueous NaOH solution and washed with diethyl ether. The aqueous phase was acidified using concentrated aqueous HCl and extracted with ethyl acetate. The organic phase was washed with brine, dried (MgSO4), filtered and concentrated to dryness to give the title compound (129 mg) as a light brown solid, MS (ESI−): m/z=374.1 [M−H]−.
