Methanol → 1,2,3,4-Tetrahydroquinoxaline

Under a nitrogen atmosphere, to a solution of lithium borohydride (741 mg) in tetrahydrofuran (50 ml), methyl iodide (1.93 ml) was added dropwise under ice cooling and stirred at room temperature for 10 minutes. To this mixture, a solution of quinoxaline (1.32 g) in tetrahydrofuran (100 ml) was added dropwise over 15 minutes and then stirred at room temperature for 5 minutes. To the reaction mixture, methanol (10 ml) was added and stirred for 5 minutes, followed by addition of additional methanol (40 ml) and stirring at room temperature for 30 minutes. After the reaction mixture was concentrated, the resulting residue was dissolved again in methanol and evaporated under reduced pressure to remove the solvent. The resulting residue was diluted with 4M aqueous sodium hydroxide (100 ml) and extracted four times with chloroform. The combined organic layers were dried over anhydrous sodium sulfate and then filtered to remove the desiccant, followed by distilling off the solvent under reduced pressure. The resulting residue was converted into a powder form by addition of n-hexane, and then collected by filtration to give the titled compound, i.e., 1,2,3,4-tetrahydroquinoxaline (1.17 g) as a light-brown crystal.

1. stirringstirred at room temperature for 5 minutes
2. stirringstirred for 5 minutes
3. stirringstirring at room temperature for 30 minutes
4. concentrationAfter the reaction mixture was concentrated
5. dissolutionthe resulting residue was dissolved again in methanol
6. customevaporated under reduced pressure
7. customto remove the solvent
8. additionThe resulting residue was diluted with 4M aqueous sodium hydroxide (100 ml)
9. extractionextracted four times with chloroform
10. dry with materialThe combined organic layers were dried over anhydrous sodium sulfate
11. filtrationfiltered
12. customto remove the desiccant
13. distillationby distilling off the solvent under reduced pressure
14. additionThe resulting residue was converted into a powder form by addition of n-hexane
15. filtrationcollected by filtration

ORD record

ord-8e14f2dbe77243d6a9d4039b8cfedcbd

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08222417B2