1,3-Benzothiazole-2-carbohydrazide → 3-Benzothiazol-2-yl-5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazine-7-carboxylic acid benzyl ester

HRID 586193Notes

Reaction equation

HRID 586193 reaction equation
[CH2:1]([O:8][C:9]([N:11]1[CH2:16][C:15](OCC)=[N:14][CH2:13][CH2:12]1)=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[S:20]1[C:24]2[CH:25]=[CH:26][CH:27]=[CH:28][C:23]=2[N:22]=[C:21]1[C:29]([NH:31][NH2:32])=O>C(O)CCC>[CH2:1]([O:8][C:9]([N:11]1[CH2:12][CH2:13][N:14]2[C:29]([C:21]3[S:20][C:24]4[CH:25]=[CH:26][CH:27]=[CH:28][C:23]=4[N:22]=3)=[N:31][N:32]=[C:15]2[CH2:16]1)=[O:10])[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 3514191,3-Benzothiazole-2-carbohydrazideHCID 542316815-Ethoxy-3,6-dihydro-2H-pyrazine-1-carboxylic acid benzyl ester

Product 1

HCID 572446703-Benzothiazol-2-yl-5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazine-7-carboxylic acid benzyl ester

Reagents, catalysts & solvents 1

HCID 2631-ButanolSolvent

Procedure

A mixture of 5-ethoxy-3,6-dihydro-2H-pyrazine-1-carboxylic acid benzyl ester (prepared according to the method of Example 259, Step A, 490 mg, 1.87 mmol) and benzothiazole-2-carboxylic acid hydrazide (360 mg, 1.87 mmol; J. Org. Chem. 1958, 23, 1344) in n-butanol (2 mL) was stirred at reflux overnight, cooled to room temperature, concentrated, and purified by flash column chromatography (1% methanol/chloroform) to give 580 mg of the title compound of Example 259, Step B (contaminated with an equimolar amount of benzothiazole-2-carboxylic acid hydrazide which was removed in the subsequent step) as a yellow solid.

Workup

  1. customprepared
  2. temperatureat reflux overnight
  3. concentrationconcentrated
  4. custompurified by flash column chromatography (1% methanol/chloroform)

Sources & evidence

ORD record
ord-2d8442d4b0984a9ca9d20939824dfc62
Source dataset
uspto-grants-2005_08
Patent number
US06936600B2

Reaction notes

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