Methylglyoxal → 3-Methylpyrido[3,4-b]pyrazine

Pyridine-3,4-diamine (2.00 g, 18.3 mmol) was dissolved in methanol (100 mL) and cooled in an ice bath. Pyruvic aldehyde (40% wt., 3.36 mL, 22.0 mmol) was added, dropwise, and the solution was allowed to warm to ambient temperature where it was stirred, under nitrogen, for 18 h. The reaction was monitored by LC-MS and pyruvic aldehyde (2.5 mL, 16.4 mmol) was added and the solution stirred at room temperature, under nitrogen for an additional 5 h. The solvent was removed, in vacuo, to give a black liquid which solidified to a black solid (3.58 g) upon standing. This material was adsorbed onto silica gel and purified by column chromatography, eluting with a solution of 1:1 hexane:ethyl acetate to give a brown solid (2.18 g, 82% Yield). 1H NMR 400 MHz (DMSO): δ=9.43 (s, 1H), 9.00 (s, 1H), 8.81 (d, 1H, J=5.9 Hz), 7.91 (dd, 1H, J=5.7 Hz, J=0.8 Hz), 2.79 (s, 3H). HPLC (Column; Xterra RP18, 3.5 μm, 4.6×150 mm, Column temp.=40° C.), Flow=1.2 mL/min., 85/15-5/95, 10 min., 5/95, 5.0 min., (25 mM HCO2NH4 buffer, pH=3.5/AcN/MeOH), No impurities @ 210-370 nM, and no impurities @ 306 nM, retention time =3.5 min. Calculated mass=145.06, [M+H]+=146.

1. temperaturecooled in an ice bath
2. additionwas added
3. stirringthe solution stirred at room temperature, under nitrogen for an additional 5 h
4. customThe solvent was removed, in vacuo
5. customto give a black liquid which
6. custompurified by column chromatography
7. washeluting with a solution of 1:1 hexane

ORD record

ord-91edde3101e941a4aeae51eab474bc02

Source dataset

uspto-grants-2010_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07696210B2