Hydrochloric Acid → Ethyl 2-(1-hydroxy-4-methyl-6-(5-nitro-1,3,4-thiadiazol-2-yloxy)-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)propanoate

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Reaction Steps

Into a 50-mL round-bottom flask were placed a solution of ethyl 2-(1,6-dihydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)propanoate (800 mg, 2.73 mmol, 1.00 equiv, 90%) in CH3CN (30 mL), KHCO3 (1.5 g, 15.00 mmol, 5.00 equiv) and 2-bromo-5-nitro-1,3,4-thiadiazole (890 mg, 3.80 mmol, 1.40 equiv, 90%). The resulting mixture was stirred overnight at room temperature. The pH value of the solution was adjusted to 4 with HCl (2 mol/L), then extracted with 4×50 mL of ethyl acetate. The organic layers were combined, washed with 2×50 mL of brine, dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column and eluted with ethyl acetate/petroleum ether (1:2). This resulted in 0.4 g (22%) of ethyl 2-(1-hydroxy-4-methyl-6-(5-nitro-1,3,4-thiadiazol-2-yloxy)-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)propanoate as a brown oil.

Provenance & Evidence