Picolinic acid → 2-(Pyridin-2-yl)-1,3-benzothiazol-5-amine

HRID 2243085Notes

Reaction equation

HRID 2243085 reaction equation
[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7](O)=O.[NH2:10][C:11]1[CH:17]=[C:16]([N+:18]([O-])=O)[CH:15]=[CH:14][C:12]=1[S-:13].[Na+].[OH-].[Na+].[Sn](Cl)Cl>Cl>[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7]1[S:13][C:12]2[CH:14]=[CH:15][C:16]([NH2:18])=[CH:17][C:11]=2[N:10]=1

Participants

6

Reactant 4

HCID 1018Picolinic acidHCID 14798Sodium Hydroxide2×HCID 24479Stannous ChlorideHCID 5488199Benzenethiol, 2-amino-4-nitro-, monosodium salt

Product 1

HCID 230857662-(Pyridin-2-yl)-1,3-benzothiazol-5-amine

Reagents, catalysts & solvents 1

HCID 313Hydrochloric AcidSolvent

Conditions

Temperature
125 °C

Procedure

PPA (500 g) is added to picolinic acid (24.6 g, 0.2 mol) and sodium 2-amino-4-nitrothiophenoxide (47 g, 0.2 mol). The mixture is heated at 120-130° C. for 6 hours. The resulting mixture is cooled and NaOH is added dropwise (pH=10). The product is filtered off and washed with water. The 2-(2-pyridyl)-5-nitrobenzothiazole is recrystallized from 9/1 isopropyl ether/methanol and is added to a solution of tin dichloride (61.6 g, 0.273 mol) in conc. HCl (50 ml) at 0° C. This mixture is heated at 95° C. for 120 minutes. It is cooled and NaOH is added dropwise (pH=10). The resulting mixture is extracted with chloroform and the combined organic phases are extracted with 0.5M HCl. The acidic aqueous phases are combined, basified with NaOH (pH=10) and extracted with ethyl acetate. The extracts are washed with water and evaporated. The solid obtained is recrystallized from isopropyl ether. Yield: 3.6 g; Rf (9/1 chloroform/methanol): 0.45; IR (KBr): 3400, 3325, 3215, 1590, 1430, 1320, 780 cm−1.

Workup

  1. temperatureThe resulting mixture is cooled
  2. filtrationThe product is filtered off
  3. washwashed with water
  4. customThe 2-(2-pyridyl)-5-nitrobenzothiazole is recrystallized from 9/1 isopropyl ether/methanol
  5. temperatureThis mixture is heated at 95° C. for 120 minutes
  6. temperatureIt is cooled
  7. extractionThe resulting mixture is extracted with chloroform
  8. extractionthe combined organic phases are extracted with 0.5M HCl
  9. extractionextracted with ethyl acetate
  10. washThe extracts are washed with water
  11. customevaporated
  12. customThe solid obtained
  13. customis recrystallized from isopropyl ether

Sources & evidence

ORD record
ord-fcbb1d4deaf34964bb7d415362c72c77
Source dataset
uspto-grants-2010_03
Patent number
US07674809B2

Reaction notes

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