Synthesis
General procedure for the synthesis of 2,4-dibromo-5-thiazolecarboxylic acid from 2,4-dibromothiazole-5-carbaldehyde: Solid potassium permanganate (2.19 g, 13.85 mmol) was added batchwise to a hot suspension of 2,4-dibromothiazole-5-carbaldehyde (2.5 g, 9.23 mmol) in water (20 mL). The reaction progress was monitored by HPLC. Potassium permanganate was continuously added until the aldehyde was completely consumed. The dark colored suspension was filtered while hot. The filtrate was cooled and acidified with concentrated hydrochloric acid. The resulting precipitate was filtered to give a white solid, which is the target product 2,4-dibromo-5-thiazolecarboxylic acid. The filtrate was lyophilized and methanol was added to dissolve the residual acid product. The suspension was filtered and the filtrate was concentrated under vacuum. The products obtained from the two treatments were combined to give 1.8 g of 2,4-dibromo-5-thiazolecarboxylic acid in 68% yield. The structure of the product was confirmed by 1H NMR (300 MHz, DMSO-d6), δ 11.87 (s, 1H).
References
[1] Organic and Biomolecular Chemistry, 2006, vol. 4, # 24, p. 4514 - 4525
[2] Patent: US2007/203210, 2007, A1. Location in patent: Page/Page column 42
