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9th September 2014 @ 01:05

Final repeat of TM 34, bringing through a large quantity of hydrazinylpyrazine to be then converted to ~10 g of 5-chlorotriazolopyrazine by the method used in Repeat synthesis of 5-chloro-[1,2,4]triazolo[4,3-a]pyrazine (TM 37-13). Pure TM 34 was obtained in 94 % yield.

scheme

 

2,6-dichloropyrazine (21 g, 141 mmol) was dissolved in EtOH (100 mL), and hydrazine hydrate (13.5 mL, 270 mmol, 2 eq) added. The reaction mixture was stirred at reflux for 6 hours, then left to stand overnight (probably not needed). The solvent was removed under reduced pressure to give a pale yellow solid. Water (~150 mL) and EtOAc (~200 mL) were added, and the mixture was shaken in an attempt to dissolve all solid. The organic layer was removed, the aqueous layer extracted with EtOAc (3 x 100 mL), and the combined organic layers washed with brine (~30 mL) before being concentrated under reduced pressure to yield pyre TM 34 as a pale yellow solid (19.13 g, 132 mmol, 94 %).

HIRAC:

34-3 hirac.pdf
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34-3 hirac.pdf
Comments
Re: Resynthesis of 2-chloro-6-hydrazinylpyrazine (TM 34-3) by Alice Williamson
9th September 2014 @ 01:47
HIRAC seen and approved. Use blast shield on large scale like this.