Methanol → Methyl 9-bromo-4,5-dihydro-[1]benzoxepino[5,4-d]thiazole-2-carboxylate
Reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[O:14][CH2:13][CH2:12][C:11]3[S:10][C:9]([C:15]([OH:17])=[O:16])=[N:8][C:7]=3[C:6]=2[CH:18]=1.OS(O)(=O)=O.[CH3:24]O>>[CH3:24][O:16][C:15]([C:9]1[S:10][C:11]2[CH2:12][CH2:13][O:14][C:5]3[CH:4]=[CH:3][C:2]([Br:1])=[CH:18][C:6]=3[C:7]=2[N:8]=1)=[O:17]Participants
4
Conditions
- Temperature
- 85 °C
Procedure
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).