Ethyl Acetoacetate → ethyl 6,7-dihydro-4-methyl-2-(4-chlorphenyl)-4H-pyrano[4,3-d]thiazole-4-acetate

HRID 258580Notes

Reaction equation

HRID 258580 reaction equation
[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[S:9][CH:10]=[C:11]([CH2:13][CH2:14][OH:15])[N:12]=2)=[CH:4][CH:3]=1.[C:16]([O:22][CH2:23][CH3:24])(=[O:21])[CH2:17][C:18]([CH3:20])=O.O.C1(C)C=CC(S(O)(=O)=O)=CC=1>C1(C)C=CC=CC=1>[CH3:20][C:18]1([CH2:17][C:16]([O:22][CH2:23][CH3:24])=[O:21])[C:10]2[S:9][C:8]([C:5]3[CH:4]=[CH:3][C:2]([Cl:1])=[CH:7][CH:6]=3)=[N:12][C:11]=2[CH2:13][CH2:14][O:15]1

Participants

5

Reactant 3

HCID 8868Ethyl AcetoacetateHCID 521998p-Toluenesulfonic acid monohydrateHCID 6105314-Thiazoleethanol, 2-(4-chlorophenyl)-

Product 1

HCID 54049665ethyl 6,7-dihydro-4-methyl-2-(4-chlorphenyl)-4H-pyrano[4,3-d]thiazole-4-acetate

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

A mixture of the starting material of formula II, 2-(4-chlorophenyl)-4-(β-hydroxyethyl)thiazole (24.0 g, 0.1 mole, described in Example 1), ethyl acetoacetate (19.5 g, 0.15 mole) and p-toluenesulfonic acid hydrate (38.0 g, 0.2 mole) in toluene (1000 ml) is heated at reflux temperature, with water separation, for 20 hr. The mixture is evaporated under reduced pressure and the residue is triturated with petroleum ether. The residue is dissolved in a mixture of aqueous sodium bicarbonate solution and ether. The organic solution is separated, washed with saturated sodium chloride solution, dried over sodium sulfate and evaporated under reduced pressure to give ethyl 6,7-dihydro-4-methyl-2-(4-chlorphenyl)-4H-pyrano[4,3-d]thiazole-4-acetate (IV, R1 = Cl, R2 = CH3, A= COOCH2CH3 and n= 1).

Workup

  1. temperatureis heated
  2. temperatureat reflux temperature
  3. customwith water separation
  4. customThe mixture is evaporated under reduced pressure
  5. customthe residue is triturated with petroleum ether
  6. dissolutionThe residue is dissolved in a mixture of aqueous sodium bicarbonate solution and ether
  7. customThe organic solution is separated
  8. washwashed with saturated sodium chloride solution
  9. dry with materialdried over sodium sulfate
  10. customevaporated under reduced pressure

Sources & evidence

ORD record
ord-ff229ec221fa46848b65072111052928
Source dataset
uspto-grants-1977_07
Patent number
US04033977

Reaction notes

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