HCID 178516710, compound → 2-Piperazin-1-YL-quinoxaline

Temperature

0 °C

2-Hydroxyquinoxaline (1.5 g) is heated in phosphorus oxychloride (10 mL) for 12 h, after which the reaction is concentrated and the residue partitioned between methylene chloride and 1 N NaOH. The resulting crude chloride is taken up in toluene (10 mL) and this solution is then added dropwise to a refluxing solution of piperazine (5 g) in toluene (40 mL). The resulting solution is refluxed for an additional 24 h, cooled to 0° C. for 0.5 h, filtered and concentrated. The filtrate is extracted with 10% acetic acid and the aqueous extracts washed with ether, basified and extracted with toluene. The toluene layer is washed with water, dried and concentrated. The concentrated material, which may alternatively be named quinoxalin-2-ylpiperazine, is placed under vacuum overnight (1.2 g, 77%, m.p. 74-76° C.). 1H NMR (CDCl3) 8.6 (s, 1H), 7.87 (dd, J=8, 1 Hz, 1H), 7.68 (dd, J=8, 1 Hz, 1H), 7.57 (ddd, J=8, 7, 1 Hz, 1H), 7.39 (ddd, J=8, 7, 1 Hz, 1H), 3.76 (t, J=5 Hz, 4H), 3.02 (t, J=5 Hz, 4H).

1. concentrationafter which the reaction is concentrated
2. customthe residue partitioned between methylene chloride and 1 N NaOH
3. additionthis solution is then added dropwise to a refluxing solution of piperazine (5 g) in toluene (40 mL)
4. temperatureThe resulting solution is refluxed for an additional 24 h
5. filtrationfiltered
6. concentrationconcentrated
7. extractionThe filtrate is extracted with 10% acetic acid
8. washthe aqueous extracts washed with ether
9. extractionextracted with toluene
10. washThe toluene layer is washed with water
11. customdried
12. concentrationconcentrated
13. customis placed under vacuum overnight (1.2 g, 77%, m.p. 74-76° C.)

ORD record

ord-462eb0bdb6644e7a84f58c94b1a837ab

Source dataset

uspto-grants-2001_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06331629B1