2-Bromo-4-methoxyphenol → diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate

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Reaction Steps

Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate. GC/MS (EI, M+) m/z 344 and 346.

Provenance & Evidence