5,6-Dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazine-7-carboxylic acid tert-butyl ester

68774-77-6

24424-99-5

723286-79-1

8-Chloro-[1,2,4]triazolo[4,3-A]pyrazine (8.10 g) obtained in Step 2 was mixed with platinum (IV) oxide and 10% palladium/carbon (2 g, 50% aqueous content) in methanol (8 mL) and placed under a hydrogen atmosphere (50 psi, Parr unit) and stirred for 34 hours. Upon completion of the reaction, the reaction mixture was filtered through a Hyflo Super Cel and the filtrate was concentrated to give an oil. The oil was dissolved in dichloromethane (200 mL) and N,N-diisopropylethylamine (10 mL) and di-tert-butyl dicarbonate (11.4 g) were added sequentially and the reaction was stirred for 3 hours at room temperature. At the end of the reaction, saturated aqueous sodium bicarbonate solution was added and extracted with chloroform three times. The organic layers were combined, dried with anhydrous sodium sulfate and concentrated. The resulting crude product was purified by silica gel column chromatography to afford 7-Boc-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-a]pyrazine (2.55 g, 22% yield).