Ethyl chloroformate → 3-Ethoxycarbonylaminothiophenol

HRID 27450

Reaction equation

HRID 27450 reaction equation
Cl[C:2]([O:4][CH2:5][CH3:6])=[O:3].[NH2:7][C:8]1[CH:9]=[C:10]([SH:14])[CH:11]=[CH:12][CH:13]=1>C(OCC)(=O)C>[CH2:5]([O:4][C:2]([NH:7][C:8]1[CH:9]=[C:10]([SH:14])[CH:11]=[CH:12][CH:13]=1)=[O:3])[CH3:6]

Participants

4

Reactant 2

HCID 10928Ethyl chloroformateHCID 315773-Aminothiophenol

Product 1

HCID 233429783-Ethoxycarbonylaminothiophenol

Reagents, catalysts & solvents 1

HCID 8857Ethyl AcetateSolvent2×

Procedure

12 ml of ethyl chloroformate are added dropwise to a solution of 25 g of 3-aminothiophenol in 150 ml of ethyl acetate at 50°, under gentle reflux. 50 ml of ethyl acetate are added and the reaction mixture is boiled under reflux for 5 minutes, cooled to 40° and filtered with suction. The filtrate is evaporated to dryness and the oily evaporation residue is chromatographed on silica gel using toluene as the solvent. 3-Ethoxycarbonylaminothiophenol is obtained by evaporating the eluate. 10 g of this product are mixed with 8 g of ethyl acetoacetate and the mixture is added dropwise to 153 g of polyphosphoric acid at 90°. The mixture is warmed for 2 hours at an internal temperature of 95° and the hot reaction mixture is poured into 2 liters of ice-water, the resulting mixture is stirred for 30 minutes and the precipitate which has separated out is filtered off with suction. 2-Methyl-7-ethoxycarbonylamino-4-oxo-4H- 1-benzothiopyran is thus obtained and after recrystallisation from 70 ml of ethanol this melts at 216°-218°. 15.6 g of this product are refluxed with 28.7 ml of sulfuric acid and 52 ml of acetic acid for 5 hours. The reaction mixture is poured into 500 ml of ice-water and the resulting mixture is neutralised with sodium hydroxide solution. 2-Methyl-7-amino-4-oxo-4H-1-benzothiopyran with a melting point of 165°-169° is obtained and this can be purified via the hydrochloride and then melts at 172°-175°.

Workup

  1. temperatureunder reflux for 5 minutes
  2. temperaturecooled to 40°
  3. filtrationfiltered with suction
  4. customThe filtrate is evaporated to dryness
  5. customthe oily evaporation residue is chromatographed on silica gel

Sources & evidence

ORD record
ord-0595e43ec12a47869061e474a7857d44
Source dataset
uspto-grants-1980_09
Patent number
US04221806

Linked notes

Loading…