Boric Acid → 2-(1H-Pyrrol-2-yl)benzo[d]thiazole

HRID 6430

Reaction equation

HRID 6430 reaction equation
[NH:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6](O)=O.[NH2:9][C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][C:11]=1[SH:16].B(O)(O)O>C1(C)C(C)=CC=CC=1.C(OCC)(=O)C>[NH:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6]1[S:16][C:11]2[CH:12]=[CH:13][CH:14]=[CH:15][C:10]=2[N:9]=1

Participants

6

Reactant 3

HCID 7628Boric AcidHCID 87132-AminothiophenolHCID 12473Pyrrole-2-Carboxylic Acid

Product 1

HCID 1356254832-(1H-Pyrrol-2-yl)benzo[d]thiazoleYield 14%

Reagents, catalysts & solvents 2

HCID 7237O-XyleneSolventHCID 8857Ethyl AcetateSolvent

Procedure

A mixture of 5.55 g (50 mmol) of pyrrole-2-carboxylic acid, 6.26 g (50 mmol) of 2-aminothiophenol and 3.09 g (50 mmol) of boric acid in 250 mL of xylene was heated under reflux for 3 days while removing water which was generated from reaction using a Dean-Stark trap. the cooled reaction mixture was diluted with 200 mL of ethyl acetate, washed with 200 mL of 5% sodium hydroxide solution and then with 200 mL of water. The separated organic layer was dried over anhydrous sodium sulfate. The resulting crude product was purified by column chromatography on silica gel with 10% ethyl acetate in hexane as eluant. The desired product, 2-(pyrrol-2-yl)benzothiazole (1.40 g, 14%) was obtained as a pale yellow solid. m.p. 150°-151° C.; 1H-NMR (CDCl3) 6.32-6.35 (m, 1H, ArH), 6.87-6.89 (m, 1H, ArH), 6.94-6.96 (m, 1H, ArH), 6.33 (t, 1H, ArH), 6.43 (t, 1H, ArH), 7.84 (d, 1H, ArH), 7.90 (d, 1H, ArH).

Workup

  1. temperaturewas heated
  2. temperatureunder reflux for 3 days
  3. customwhile removing water which
  4. customwas generated from reaction
  5. customthe cooled reaction mixture
  6. washwashed with 200 mL of 5% sodium hydroxide solution
  7. dry with materialThe separated organic layer was dried over anhydrous sodium sulfate
  8. customThe resulting crude product was purified by column chromatography on silica gel with 10% ethyl acetate in hexane as eluant

Sources & evidence

ORD record
ord-514be903fc7a4ed1b961eb5abfbc5505
Source dataset
uspto-grants-1993_09
Patent number
US05248782

Linked notes

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