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22nd March 2018 @ 14:50

Method:

2-chloro-6-(2-hydrazinyl(4-bromobenzylidene))pyrazine) (C) (100.2, 0.322 mmol, 1.0 equiv) was dissolved in dry dichloromethane (15 mL) forming a pale yellow solution. Diacetoxyiodobenzene (PIDA) (114 mg, 0.354 mmol, 1.1 equiv) was then added and the solution was stirred at room temperature under nitrogen for approximately 16 hours. After this time, the reaction mixture was exposed to air and analysed by TLC (pure EtOAc) showing a clear product peak as well as some residual PIDA. The reaction mixture was quenched by the addition of a saturated aqueous solution of sodium hydrogen carbonate (~15 mL). Aqueous layers were separated and then extracted with DCM (2 x 15 mL). The organic layers were combined and washed with brine (1 x 20 mL), dried with MgSO4, filtered and evaporated in vacuo, yielding the crude product as pale yellow crystals (69.6 mg, 70.2%). The crude product was characterised using 1H NMR, 13C NMR, DEPT 90 + 135, GC-MS and IR. The purified product was isolated using a silica plug since TLC showed the presence of the product and PIDA with significant separation.


Attached Files
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4-bromo triazolopyrazine formation 1H NMR.pdf