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To a solution of 5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine hydrochloride (1.0 g, 6.23 mmol) in CH2Cl2 (25 mL) were added Et3N (2.17 mL, 15.57 mmol) and Boc2O (1.52 mL, 6.54 mmol) and the reaction was stirred at room temperature overnight. The mixture was extracted with aqueous 0.25 M KHSO4 (50 mL). The organic layer was dried (Na2SO4) and evaporated to dryness to afford compound A48-1 (1.29 g, 92percent).
92%
With triethylamine In dichloromethane at 20℃;
Procedure for step-1:To a solution of 5, 6, 7 , 8-tetrahydro- [ 1, 2 , 4 ] triazolo [ 4 , 3- ajpyrazine hydrochloride (1.0 g, 6.23 irunol) in CH2CI2 (25 itiL) were added Et3N (2.17 mL, 15.57 mmol) and BoC2O (1.52 itiL, 6.54 mmol) and the reaction was stirred at room temperature overnight. The mixture was extracted with aqueous 0.25 M KHSO4 (50 mL) . The organic layer was dried (Na2SO4) and evaporated to dryness to afford compound A48-1 (1.29 g, 92percent) .
Stage #1: With platinum(IV) oxide; palladium 10% on activated carbon; hydrogen In methanol for 34 h; Stage #2: With N-ethyl-N,N-diisopropylamine In methanol at 20℃; for 3 h;
After dissolution compound obtained in Step 2 (8.10 g) and platinum oxide (IV) and 10percent palladium / carbon (2g, 50percent water content) in methanol (8 mL), under an atmosphere of hydrogen 50psi (Parr) 34 time and stirred. After filtering the reaction solution at Hyflo Super Cel, the oil obtained by concentrating the solvent was dissolved in dichloromethane (200 mL), N, N-diisopropylethylamine (10 mL) and di-tert-butylcarbonate (11 .4g) was added was stirred for 3 hours at room temperature. The reaction solution was extracted three times with chloroform after adding a saturated aqueous sodium hydrogen carbonate solution, and the organic layer was concentrated after dried over sodium sulfate. The resulting residue to give the title compound purified by silica gel column chromatography (2.55g, 22percent).
5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine[ No CAS ]
[ 723286-79-1 ]
Yield
Reaction Conditions
Operation in experiment
With N-ethyl-N,N-diisopropylamine; In dichloromethane; at 20℃; for 2h;
To a solution of 9.70 g (76.2 mmol) of 5,6, 7,8-tetrahydro [1, 2,4] triazolo [4,3- AJPYRAZINE in 250 mL of dichloromethane was added sequentially 11.8 g (91.4 mmol) of N, N diisopropylethylamine and 18.3 g (83.8 mmol) of di-tert-butyl dicarbonate. The reaction was stirred at ambient temperature for 2 h. The reaction mixture was then washed sequentially with saturated aqueous sodium bicarbonate solution and brine, dried over magnesium sulfate, and concentrated in vacuo. The residue was azeotroped with hexanes and the resultant solid triturated with a mixture of hexanes/ethyl acetate (95: 5) to afford the title compound. LC/MS 225. 1 (M+1).
With N-Bromosuccinimide; sodium hydrogencarbonate; In chloroform; at 0 - 20℃; for 2h;
The compound obtained in Step 3 (1 g) was dissolved in chloroform (20 mL), sodium bicarbonate (688 mg) and N- bromosuccinimide (873 mg) was added at 0 C., the-reaction solution was stirred for 2 hours at room temperature and extracted 3 times with chloroform after addition of water, the organic layer gave the title compound by the residue obtained, which was concentrated after drying over sodium sulfate and purified by silica gel column chromatography (693mg, 51%). LRMS (ESI) m / z 303 [M + H] +.
With N-Bromosuccinimide; sodium hydrogencarbonate; In chloroform; at 0 - 20℃; for 16h;
To a solution of 9.01 g (40.0 mmol) of 7- (tert-butoxycarbonyl)-5, 6,7, 8- tetrahydro [1, 2,4] triazolo [4, 3-a] pyrazine in 150 mL chloroform was added 6.72 g (80.0 mmol) of sodium bicarbonate. The system was cooled to 0 C and 7.11 g (40.0 mmol) OF N- bromosuccinimide was added. The reaction was stirred at 0 C for 15 min and at ambient temperature for 16 h. The reaction was diluted with dichloromethane and washed sequentially with saturated aqueous sodium bicarbonate solution and brine, dried over magnesium sulfate, and concentrated in vacuo. The crude product was purified by flash chromatography on a BIOTAGE system (silica gel, 4% methanol/ethyl acetate) to yield the title compound. LC/MS 303.0 and 305.0 (M+1).
To a solution of compound A48-1 (1.29 g, 5.75 mmol) in dry THF (50 mL) was added a solution of 2.5 M n-BuLi in hexane (2.53 mL, 6.33 mmol) at -78 C. under argon. After 15 min ethyl formate (702 muL, 8.63 mmol) was added and the reaction mixture was stirred for 15 min at -78 C. Saturated aqueous NH4Cl (150 mL) was added and the mixture was extracted with CH2Cl2 (3×100 mL). The combined organic layer was dried (Na2SO4) and evaporated to dryness to afford aldehyde A48-2 (1.21 g, 83%).
83%
Procedure for step-2 :To a solution of compound A48-1 (1.29 g, 5.75 mmol) in dry THF (50 mL) was added a solution of 2.5 M ?-BuLi in hexane (2.53 mL, 6.33 mmol) at -78 C under argon. After 15 min ethyl formate (702 muL, 8.63 mmol) was added and the reaction mixture was stirred for 15 min at -78 0C. <n="143"/>Saturated aqueous NH4Cl (150 mL) was added and the mixture was extracted with CH2CI2 (3 x 100 mL) . The combined organic layer was dried (Na2SO4) and evaporated to dryness to afford aldehyde A48-2 (1.21 g, 83%).
5,6,7,8-tetrahydro-(1,2,4)triazolo(4,3-a)-pyrazine hydrochloride[ No CAS ]
[ 723286-79-1 ]
Yield
Reaction Conditions
Operation in experiment
92%
With triethylamine; In dichloromethane; at 25℃;
To a solution of 5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine hydrochloride (1.0 g, 6.23 mmol) in CH2Cl2 (25 mL) were added Et3N (2.17 mL, 15.57 mmol) and Boc2O (1.52 mL, 6.54 mmol) and the reaction was stirred at room temperature overnight. The mixture was extracted with aqueous 0.25 M KHSO4 (50 mL). The organic layer was dried (Na2SO4) and evaporated to dryness to afford compound A48-1 (1.29 g, 92%).
92%
With triethylamine; In dichloromethane; at 20℃;
Procedure for step-1:To a solution of 5, 6, 7 , 8-tetrahydro- [ 1, 2 , 4 ] triazolo [ 4 , 3- ajpyrazine hydrochloride (1.0 g, 6.23 irunol) in CH2CI2 (25 itiL) were added Et3N (2.17 mL, 15.57 mmol) and BoC2O (1.52 itiL, 6.54 mmol) and the reaction was stirred at room temperature overnight. The mixture was extracted with aqueous 0.25 M KHSO4 (50 mL) . The organic layer was dried (Na2SO4) and evaporated to dryness to afford compound A48-1 (1.29 g, 92%) .
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