2-Methylquinoxaline → (2S)-1,2,3,4-Tetrahydro-2-methylquinoxaline

Temperature

40 °C

To an argon-purged pressure-resistant glass vessel (100 mL) equipped with a magnetic stir bar, RuCl[(R)-daipena][(R)-dm-segphos] (3.1 mg, 2.6 μmol) and KO(t-Bu) (14.1 mg, 0.126 mmol) were added, and the vessel was purged with argon again. To this vessel, a toluene (2.5 mL) solution containing 2-methylquinoxaline (355.4 mg, 2.47 mmol) and being degassed by the freeze-pump-thaw technique in advance was added by pressure transfer using a cannula. An operation in which hydrogen was introduced into the pressure-resistant vessel up to 0.8 MPa and then released was repeated 10 times to completely substitute the inside with hydrogen. Then, hydrogen was introduced up to 2.0 MPa, and the vessel was stirred in a water bath at 40° C. for 13 hours. After hydrogen was released, the solution was concentrated under reduced pressure, and the residue was purified through a silica gel short path column (hexane:ethyl acetate=1:1) to obtain (S)-1,2,3,4-tetrahydro-2-methylquinoxaline (355.1 mg, 970). A result of an analysis conducted by gas chromatography (column: CHIRASIL-DEX CB) showed that the optical purity of this product was 99% ee or higher.

1. customTo an argon-purged pressure-resistant glass vessel (100 mL)
2. customequipped with a magnetic stir bar
3. customthe vessel was purged with argon again
4. custombeing degassed by the freeze-pump-thaw technique in advance
5. additionwas added by pressure transfer
6. additionAn operation in which hydrogen was introduced into the pressure-resistant vessel up to 0.8 MPa
7. additionThen, hydrogen was introduced up to 2.0 MPa
8. concentrationthe solution was concentrated under reduced pressure
9. customthe residue was purified through a silica gel short path column (hexane:ethyl acetate=1:1)

ORD record

ord-41b9183a5c024eecbb66695bfbddfce1

Source dataset

uspto-grants-2016_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09328079B2