Sodium Hydroxide → [5-(8-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulen-2-yl)-1-isopropyl-1H-[1,2,4]triazol-3-yl]-carbamic acid benzyl ester

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To a suspension of 8-bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid (1.86 g, 5.70 mmol) in anhydrous THF (75 mL) was added diisopropylethylamine (2 mL, 11.4 mmol), HATU (2.39 g, 6.27 mmol) and 1-benzyloxycarbonyl-2-methyl-isothiourea (1.47 g, 6.56 mmol) at RT. After stirring for 24 hours an aqueous saturated sodium bicarbonate solution was added and the mixture extracted with 1:1 EtOAc/THF solution (×2). The organic layers were combined, washed with brine, dried (Na2SO4) and concentrated in vacuo. The resulting solid was added to DMF (50 mL) and treated with diisopropylethylamine (4 mL, 22.8 mmol) and isopropylhydrazine hydrochloride (941 mg, 8.55 mmol). The mixture was heated to 95° C. and scrubbed with 1N NaOH solution and NaOCl solution. After 2 hours the mixture was allowed to cool to RT, extracted with EtOAc and washed with water. The organic layer was dried (Na2SO4) and concentrated in vacuo. The resultant residue was purified by flash chromatography (SiO2, gradient 0-50% EtOAc in cyclohexane) to afford [5-(8-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulen-2-yl)-1-isopropyl-1H-[1,2,4]triazol-3-yl]-carbamic acid benzyl ester (1.75 g, 57%). LCMS: RT=5.11 min, [M+H]+=540/542

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