Reaction #662230

Reaction equation

9-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid

MeOH

H2SO4

→

9-Bromo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester

Yield 57.0%

Conditions

Workup

1. 1
   TemperatureThen the mixture was heated
2. 2
   Filtrationwas filtered
3. 3
   Washthe solid was washed with saturated aqueous NaHCO3 solution
4. 4
   Otherdried in vacuo

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).

Source