Water → Ethyl 2-amino-alpha-methylbenzothiazole-6-acetate

HRID 34533Notes

Reaction equation

HRID 34533 reaction equation
[NH2:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]([CH3:14])[C:9]([O:11][CH2:12][CH3:13])=[O:10])=[CH:4][CH:3]=1.[N-:15]=[C:16]=[S:17].[K+].BrBr.O>C(O)(=O)C>[NH2:15][C:16]1[S:17][C:7]2[CH:6]=[C:5]([CH:8]([CH3:14])[C:9]([O:11][CH2:12][CH3:13])=[O:10])[CH:4]=[CH:3][C:2]=2[N:1]=1

Participants

6

Reactant 4

HCID 962WaterHCID 24408BromineHCID 118009Ethyl 2-(4-aminophenyl)propanoateHCID 10931372Isothiocyanatopotassium

Product 1

HCID 13477940Ethyl 2-amino-alpha-methylbenzothiazole-6-acetateYield 48.5%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent2×

Procedure

The said starting material was also prepared by dissolving 154.6 g of ethyl 2-(p-aminophenyl)propionate [Arzneim. Forsch, Vol. 23, p. 1090 (1973)] in 95% acetic acid and 261 g of potassium isothiocyanate were added with stirring. A solution of 149.4 g of Br2 in 750 ml of 95% acetic acid was then added dropwise at 18°-25° C. over 2 hours and the mixture was stirred for an extra half hour, then poured into 8 liters of water. The mixture was filtered through celite and then neutralized to pH 5-6 using 6+ liters of 20% Na2CO3 solution. The product was then extracted with CH2Cl2 and the organic layer was separated, washed with water, dried over MgSO4 and finally filtered and evaporated to dryness. The crude product was dissolved in 300 ml of hot ethyl acetate and an equal volume of petroleum ether (40°-60° C.) was added. On cooling, cream colored crystals were formed which were filtered off, washed with ethyl acetate/petroleum ether and dried to obtain 97 g (48.5% yield) of the ethyl 2-amino-α-methylbenzothiazole-6-acetate melting at 146° C. A second crop of 29 g was obtained from the mother liquors for a total yield 63%.

Workup

  1. customwas also prepared
  2. additionwere added
  3. stirringthe mixture was stirred for an extra half hour
  4. filtrationThe mixture was filtered through celite
  5. extractionThe product was then extracted with CH2Cl2
  6. customthe organic layer was separated
  7. washwashed with water
  8. dry with materialdried over MgSO4
  9. filtrationfinally filtered
  10. customevaporated to dryness
  11. dissolutionThe crude product was dissolved in 300 ml of hot ethyl acetate
  12. additionan equal volume of petroleum ether (40°-60° C.) was added
  13. temperatureOn cooling
  14. customcream colored crystals were formed which
  15. filtrationwere filtered off
  16. washwashed with ethyl acetate/petroleum ether
  17. customdried

Sources & evidence

ORD record
ord-65819556d5844351966c28800388618a
Source dataset
uspto-grants-1988_08
Patent number
US04762840

Reaction notes

Loading…