N-bromobutanimide → HCID 67198034, compound

Participants

Reaction Steps

Methyl 3-[(pivaloyl)oxy]-4-oxo-4H-pyrido[1,2-a]pyrimidine-2-carboxylate (see Example 1, Step 2a) and NBS (5 eqs.) were dissolved in a 3:1 mixture of acetonitrile and acetic acid. The solution was left standing at 5° C. with occasional shaking for 4 days. The solvents were removed under reduced pressure and the residue was suspended in chloroform. The precipitate was removed by filtration and the solution concentrated under vacuum. The residue was dissolved in dichloromethane, and triethylamine (7 eqs.) was added. The mixture was stirred for 1.5 hours at room temperature, the solvent removed under vacuum, and the residue partitioned between EtOAc and 1N aqueous HCl. The organic phase was washed with 1N aqueous HCl and the combined aqueous phases extracted with EtOAc. The combined organic phases were washed with water, dried over Na2SO4, filtered and concentrated under reduced pressure. The product was isolated by flash chromatography (SiO2, eluant: PE/EtOAc, 4.5:5.5). The product was obtained as a light yellow solid.

Provenance & Evidence