Hydrochloric Acid → ethyl (2E)-2H-1,4-benzothiazin-3(4H)-ylideneethanoate

HRID 491345Notes

Reaction equation

HRID 491345 reaction equation
[N+]([C:4]1[CH:12]=[CH:11][C:7]2[N:8]=[CH:9][S:10][C:6]=2[CH:5]=1)([O-])=O.[OH-].[K+].ClC[C:17](=O)[CH2:18][C:19]([O:21][CH2:22][CH3:23])=[O:20].Cl>CCO>[S:10]1[C:6]2[CH:5]=[CH:4][CH:12]=[CH:11][C:7]=2[NH:8]/[C:17](=[CH:18]/[C:19]([O:21][CH2:22][CH3:23])=[O:20])/[CH2:9]1

Participants

6

Reactant 4

HCID 313Hydrochloric AcidHCID 14797Potassium HydroxideHCID 69484Ethyl 4-chloroacetoacetateHCID 762566-Nitrobenzothiazole

Product 1

HCID 5303657ethyl (2E)-2H-1,4-benzothiazin-3(4H)-ylideneethanoateYield 70%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Conditions

Temperature
0 °C

Procedure

steps 1 and 2—To a solution of 6-nitrobenzothiazole (10, 10.2 g, 57 mmol) in EtOH (500 mL) was added KOH (7.0 g, 125 mmol). The reaction was heated at reflux for 15 min then cooled to 0° C. Ethyl chloroacetoacetate (9.3 g, 57 mmol) was added and the mixture stirred at RT for 1 h. The reaction mixture was poured into 1N HCl (500 mL) and the resulting solid was collected. The solid was dissolved in EtOAc. The organic phase was washed with brine, dried (MgSO4) and the solvent was removed under reduced pressure. The product was purified by SiO2 chromatography eluting with 10% EtOAc/hexane to afford 0.61 g (70%) of 12a: LCMS RT 3.48 min, M+H.

Workup

  1. temperatureThe reaction was heated
  2. temperatureat reflux for 15 min
  3. customthe resulting solid was collected
  4. dissolutionThe solid was dissolved in EtOAc
  5. washThe organic phase was washed with brine
  6. dry with materialdried (MgSO4)
  7. customthe solvent was removed under reduced pressure
  8. customThe product was purified by SiO2 chromatography
  9. washeluting with 10% EtOAc/hexane

Sources & evidence

ORD record
ord-b0b64ef1a0fa497ca81a3b2350740764
Source dataset
uspto-grants-2009_05
Patent number
US07531534B2

Reaction notes

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