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10th September 2014 @ 05:48

Bringing through a substantial amount of chloro-triazolopyrazine for future work. Also, using lower excesses of orthoformate and TsOH in the hope that this gives a cleaner product (if not, more will be added later).

 

scheme

 

2-chloro-6-hydrazinylpyrazine (from Resynthesis of 2-chloro-6-hydrazinylpyrazine (TM 34-3): 8.00 g, 55.3 mmol) was dissolved in toluene (150 mL), triethyl orthoformate (18.3 ml, 110 mmol, 2 eq) and TsOH (500 mg, 2.76 mmol, 10 mol %) added, and the reaction mixture refluxed (bath temp 110 oC) for 24 h. Solvents removed under reduced pressure, and purified by FCC (EtOAc, hexanes) to give nearly-pure TM 37-14 (5.30 g, 35.4 mmol, 62 %), which was recrystallised from EtOAc to give pure TM 37-14 (3.85 g, 45 % overall).

 

HIRAC: see Synthesis of 5-chloro-[1,2,4]triazolo[4,3-a]pyrazine (TM 37-1)

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