Potassium Hydroxide → 4,6-Dimethylpyridoimidazolone

Participants

Reaction Steps

In a 250-mL three-necked flask containing methanol (42 mL) fitted with an overhead stirrer is added 2-amino-4,6-dimethylnicotinamide (8a) (3.0 g, 0.018 mol) as a solid at 23° C. under a nitrogen atmosphere. The resulting mixture is stirred at room temperature under a nitrogen atmosphere for five minutes to dissolve 8a a completely. The solution is cooled to -20° C. before the addition of 9a. To the clear, colorless solution of 8a at -20° C. is added the solution of 9 [prepared from 0.018 mol of N-bromosuccinimide and 0.045 mol of potassium hydroxide in water (18 mL)]via a double-tipped needle under a nitrogen atmosphere. The solution of 9a must be maintained at -5° C. during the addition in order to prevent decomposition to 13 and rearrangement to 15. The resulting mixture is aged at -20° C. for 5 hours. The product 10a precipitates out of the reaction mixture during the age. The reaction mixture is filtered and the filter cake is washed with water (10 mL) and vacuum dried to afford 2.39 g of 10a as a white solid in 81% yield. The purity is 99 W % by HPLC as compared to a recrystallized sample of 10a and the A % purity is 99%. The amount of product in the mother liquors is 321 mg(11%) by assay. The mother liquor also contains 274 mg of 8a (9%) by assay. ##STR41##

Provenance & Evidence