Methanol → Methyl 9-bromo-4,5-dihydro-[1]benzoxepino[5,4-d]thiazole-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a stirred mixture of 9-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid (20.0 g, 61.3 mmol) in MeOH (280 mL), was added H2SO4 (45.1 g, 450 mmol) dropwise at room temperature. Then the mixture was heated to reflux (85° C.) mixture was filtered and the solid was washed with saturated aqueous NaHCO3 solution, dried in vacuo to afford 9-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester (12 g, 57%) as a yellow solid which was directly used for the next step without any further purification. LC-MS: 341.8 (M+2).

Provenance & Evidence