Benzoyl Peroxide → 4-Bromomethyl-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic Acid Ethyl Ester

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To a 2-L round-bottom flask equipped with an mechanical overhead stirrer, a reflux condenser and a N2inlet was added ethyl 4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazole-5-carboxylate (85g, 0.27moles, 1.0eq) and dry carbon tetrachloride (750ml, 0.38M). Freshly recrystallized N-bromo succinimide (52.72g, 1.1eq) was added as a solid, Benzoyl peroxide (6.5g, 10mol %) was added at room temperature all at once as a solid, and the reaction mixture was refluxed for 5hrs. The reaction was monitored by 1H NMR and was determined to be composed of a 9:1mixture of mono-bromination product (i.e. desired product) and di-bromination product with a 90% conversion. After cooling to 0° C. (to precipitate out the succinimide) the reaction was filtered through Celite and the solvent was removed under reduced pressure to yield a brown oil. The oil was crystallized using hexanes to yield 100g (94%) of an off-white product of 90% purity.

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