(2S)-2-methyl-1,2,3,4-tetrahydroquinoxaline

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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. To an argon-purged pressure-resistant glass vessel (100 mL) equipped with a magnetic stir bar the vessel was purged with argon again being degassed by the freeze-pump-thaw technique in advance was added by pressure transfer An operation in which hydrogen was introduced into the pressure-resistant vessel up to 0.8 MPa Then, hydrogen was introduced up to 2.0 MPa the solution was concentrated under reduced pressure the residue was purified through a silica gel short path column (hexane:ethyl acetate=1:1)

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 1-L round bottomed flask containing (S)-2-(2-aminophenylamino)propane-1-ol (5.12 g, 30.8 mmol) was charged with acetonitrile (400 mL). The solution was concentrated partially in order to azeotropically dry the solution (ca. 100 mL of acetonitrile were removed). Triphenylphosphine (17.77 g, 67.8 mmol) was added, and once the triphenylphosphine had dissolved, carbon tetrabromide (22.47 g, 67.8 mmol) was added. The internal temperature gradually increased to a high of 35° C. After 10 min, triethylamine (18.89 mL, 136 mmol) was added. After 15 min, the reaction mixture was heated to 80° C. After 4 h, heating was discontinued and the reaction mixture stirred at rt overnight. The reaction mixture was diluted with aqueous sodium hydroxide and the mixture stirred at rt until hydrolysis of the iminophosphorane was complete. The mixture was extracted with dichloromethane. The dichloromethane extract was concentrated under reduced pressure. The crude product was purified by flash chromatography on silica gel. The product-containing fractions were concentrated to afford (S)-2-methyl-1,2,3,4-tetrahydroquinoxaline (1.9 g, 41%). MS (ESI, pos. ion) m/z 149 [M+1]+. The solution was concentrated partially in order to azeotropically dry the solution (ca. 100 mL of acetonitrile were removed) After 15 min the reaction mixture was heated to 80° C After 4 h heating The mixture was extracted with dichloromethane The dichloromethane extract was concentrated under reduced pressure The crude product was purified by flash chromatography on silica gel The product-containing fractions were concentrated

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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. To an argon-purged pressure-resistant glass vessel (100 mL) equipped with a magnetic stir bar the vessel was purged with argon again being degassed by the freeze-pump-thaw technique in advance was added by pressure transfer An operation in which hydrogen was introduced into the pressure-resistant vessel up to 0.8 MPa Then, hydrogen was introduced up to 2.0 MPa the solution was concentrated under reduced pressure the residue was purified through a silica gel short path column (hexane:ethyl acetate=1:1)