methyl 6-bromo-5-chloropyrazine-2-carboxylate synthesis

Yield:1017603-87-0 29%

Reaction Conditions:

with trichlorophosphate for 3 h;Heating / reflux;

Steps:

10.b

b) 6-Bromo-5-chloro-pyrazine-2-carboxylic acid methyl ester; A mixture of 6-bromo-5-hydroxy-pyrazine-2-carboxylic acid methyl ester and 9.75 mL (10.7 mmol) POCl₃ was refluxed for 3 h and subsequently quenched with 200 g ice. The mixture was extracted with DCM, the combined organic phases were dried with MgSO₄ and evaporated to dryness the residue was purified by column chromatography on silica eluting with a gradient formed from ethyl acetate and heptane. The product fractions were combined and evaporated to dryness to yield 0.95 g (29%) of the title compound as light yellow solid. 300-MHz-¹H-NMR (DMSO): δ=9.00 (s, 1H, 3-H), d=4.04 (s, 3H, OMe).

References:

US2008/85905,2008,A1 Location in patent:Page/Page column 14