I got 2,6-dibromopyrazin and i want to synthesise pyrazine-2,6-dicarbonitrile.
I already tried with CuCN/NaCN in DMF (Reflux, on), according to a literature procedure for pyridine-2,6-dicarbonitrile (DOI: 10.1039/C4DT00341A) and also with Pd(PPh3)4/Zn(CN)2 in DMF (reflux, on).
Does anyone have another suggestion for me, how to synthesis pyrazine-2,6-dicarbonitrile?
Thanks in advance!
An alternative could be use the method for palladium-catalyzed cyanation of aromatic bromides promoted by low-level tri-n-butyltin chloride or cyanide and KCN as the cyanide source. (Yang and Wiliams, Organic Letters, 2004).
Yang and Williams reported that only trace levels of the tri-n-butyltin compound are required to achieve high conversion and yield in the cyanation of aryl bromides, iodides, and triflates under mild conditions.
Org. Lett. 2004, 6, 17, 2837-2840.
This article may be useful to you.
Series of substituted phthalonitriles (4,5-bis[2'-(2''-benzyloxyethoxy)ethoxy]phthalonitrile, 4,5-bis(2-ethoxyethoxy) phthalonitrile and 4',5',4'',5''-tetracyanodibenzo-24-crown-8) was obtained by means of Pd-catalyzed cyanation reaction in high yields. Analysis of the obtained results together with previously reported data concerning transition metal catalyzed synthesis of phthalonitriles and analogues reveals advantages of each of these methods in comparison with classical approaches - ammonolysis/dehydratation and Rosenmund-Braun cyanation.
https://macroheterocycles.isuct.ru/ru/system/files/mhc2013_t06n1_23-32.pdf
Maintain Anhydrous condition with degassed the reaction mixture with nitrogen 10 mins before adding palladium catalyst.
Or you can add CuI 10mol% and CuCN 4eq and stir at 120 degrees in DMF under argon atm.
Refer to our publication," synthesis of phthalonitriles using a palladium catalyst".
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