5,7-dichloropyrido[3,4-b]pyrazine-2,3(1H,4H)-dione synthesis

Yield:168123-76-0 543 mg (73%)

Reaction Conditions:

with aq NaOH;oxalic acid in hydrogenchloride;

Steps:

8 6-Aza-5,7-dichloro-1,4-dihydroquinoxaline-2,3-dione (25)

6-Aza-5,7-dichloro-1,4-dihydroquinoxaline-2,3-dione (25) A solution of the diamine 24 (564 mg, 3.2 mmol) and oxalic acid (400 mg, 4.4 mmol) in 2N HCl (6.5 mL) was refluxed for 3 h, then allowed to cool to room temperature. The resulting precipitate was filtered and washed with water (2*5 mL). The wet product was stirred with 40 mL of 0.5N aq NaOH for 0.5 h, then filtered. The filtrate was acidified to pH 5 with 2N HCl. The precipitate was filtered, washed with H₂₀, and dried to give 543 mg (73%) of 25 as a yellow powder, mp 318°-20° C. ¹ H NMR (DMSO-d₆) δ 7.039 (s, 1H), 11.756 (bs, 1H), 12.398 (bs, 1H). HRMS, Calcd for C₇ H₃ Cl₂ N₃ O₂ 230.9610; Found 230.9619. Purity was 100% based on HPLC.

References:

US5620978,1997,A