Acetamidine monohydrochloride → 2-methyl-6-phenyl-5-propargyl-4(3H)-pyrimidinone

Participants

Reaction Steps

To a stirred suspension of 8.00 g (84.6 mmol) of acetamidine hydrochloride in 100 mL of methanol was added 4.56 g (84.4 mmol) of solid sodium methoxide. The mixture was stirred for 40 min at room temperature and rotovaped to remove the methanol. The residue was suspended in 75 mL of ethanol and a solution of 6.19 g(26.9 mmol) of ethyl 2-benzoyl-pent-4-ynoate in 75 mL of toluene was added. The mixture was heated to reflux with a Dean Stark trap and the first 80 mL of distillate was collected and discarded. An 80 mL portion of toluene was added and the mixture was heated at reflux for two weeks. The mixture was allowed to cool, diluted with 70 mL of ether and extracted with two 50 mL portions of 5% aqueous sodium hydroxide. The aqueous extracts were acidified to pH 1 and washed with two 75 mL portions of ethyl acetate. The pH of the aqueous phase was adjusted to 10 and the white precipitate that formed was collected by filtration. Drying furnished 1.76 g (29%) of 2-methyl-6-phenyl-5-propargyl-4(3H)-pyrimidinone, mp 220°-225° C., 1H-NMR (d6-DMSO) δ2.3 (3H, s), 2.68(1H, t,J=4), 3.20(2H, d,J=4), 7.45(3H,m), 7.65 (2H,m).

Provenance & Evidence