2H-Pyrido[3,2-b]-1,4-oxazin-3(4H)-one

2-Amino-3-ol (45 mmol) and sodium hydrogen carbonate (51 mmol) in water (30 ml) and 2-butanone (30 ml) mixed solution. Under ice-cooling, chloroacetyl chloride (51 mmol) of 2-butanone (10 ml) was slowly added, maintaining the temperature during the addition does not exceed 10 ° C. It was stirred at room temperature for 30 minutes, stirring for 1 hour at 75 ° C, and concentrated recrystallization (methanol / water = 1: 1) to give 4.3 g of the title compound.General procedure: To a stirred solution of 2a (2 mmol) in acetic acid (10 mL), powdered Fe (12 mmol) was added and the reaction mixture was then refluxed for 2 h. The progress of the reaction was monitored by TLC. After completion of the reaction, the reaction mixture was cooled to room temperature and the acetic acid was removed under reduced pressure, EtOAc (20 mL) was added and was stirred for 2 min and then filtered to remove any iron impurities. The insoluble iron residue was washed with EtOAc (20 mL). The filtrate and washings were combined and dried over anhydrous MgSO4. The solvent was removed under reduced pressure and the crude product thus obtained was purified by column chromatography to obtain the pure product 3a.A mixture of 3-hydroxy-2-aminopyridine 2 (3 g, 27 mmol), tert-butylbromoacetate3 (4 mL, 27 mmol), Adogen-464 (168 mg) and NaOH solution (40percent in water, 15 mL) was dissolved in DCM (25 mL).The reaction mixture was stirred at room temperature for 24 h. Themixture was then washed with water (3 × 50 mL) and the organic layerscombined. The organic portion was dried, (MgSO4) and concentratedin vacuo. The resulting crude yellow oil was purified by columnchromatography (silica gel, 3percent MeOH in DCM) to afford amine 4:Yellow oil; yield 2.3 g, 38percent; Rf (5percent MeOH in DCM) 0.50; IR (νmax, cm–1) film: 3483 (w), 1748 (s), 1616 (s), 1476 (s), 1154 (s); 1H NMR(300 MHz, CDCl3) δ 7.67 (1H, d, J = 5 Hz, H py), 6.80 (1H, d, J = 8 Hz, H py), 6.55 (1H, dd, J = 8, 5 Hz, H py), 4.85 (2H, br. s, NH2), 4.49 (2H, s, CH2), 1.45 (9H, s, 3 × CH3); 13C NMR (75 MHz, CDCl3) δ 167.7 (s), 150.7 (s), 140.9 (s), 140.1 (d), 117.7 (d), 113.3 (d), 82.9 (s), 66.3 (t), 28.2(q); LRMS (ES) m/z (percent): 266 [M + H + CH3CN]+ (30).3–5

Molecular Weight:150.13
XLogP3:0.1
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:3
Exact Mass:150.042927438
Monoisotopic Mass:150.042927438
Topological Polar Surface Area:51.2
Heavy Atom Count:11
Complexity:172
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes