1-Piperazinecarboxylic acid, ethyl ester → Ethyl 4-(6-chloro-3-nitropyridin-2-yl)piperazine-1-carboxylate
Reaction equation
Cl[C:2]1[C:7]([N+:8]([O-:10])=[O:9])=[CH:6][CH:5]=[C:4]([Cl:11])[N:3]=1.[CH2:12]([O:14][C:15]([N:17]1[CH2:22][CH2:21][NH:20][CH2:19][CH2:18]1)=[O:16])[CH3:13]>>[Cl:11][C:4]1[N:3]=[C:2]([N:20]2[CH2:19][CH2:18][N:17]([C:15]([O:14][CH2:12][CH3:13])=[O:16])[CH2:22][CH2:21]2)[C:7]([N+:8]([O-:10])=[O:9])=[CH:6][CH:5]=1Participants
Procedure
2,6-Dichloro-3-nitropyridine was reacted with N-ethoxycarbonylpiperazine to give 6-chloro-2-(4-ethoxycarbonyl-1-piperazinyl)-3-nitropyridine. The product, without purification, was heated with ethanolic ammonia in an autoclave at 120°-125° C. to give 6-amino-2-(4-ethoxycarbonyl-1-piperazinyl)-3-nitropyridine (mp 132°-134° C.), which was treated with acetic anhydride in acetic acid to give 6-acetylamino-2-(4-ethoxycarbonyl-1-piperazinyl)-3-nitropyridine (mp 168°-169° C.). This compound was catalytically hydrogenated in the presence of 5% palladium-carbon in acetic acid to yield 3-amino-6-acetylamino-2-(4-ethoxycarbonyl-1-piperazinyl)pyridine. The obtained 3-amino derivative, without further purification, was dissolved in a mixture of ethanol and 42% tetrafluoroboric acid, and to this solution was added a solution of isoamyl nitrite in ethanol at below 0° C. with stirring. Twenty minutes later, ether was added to the solution. The resulting precipitate was collected by filtration and washed with a mixture of methanol and ether and then with chloroform to yield 6-acetylamino-2-(4-ethoxycarbonyl-1-piperazinyl)-3-pyridine diazonium tetrafluoroborate; mp 117°-117.5° C. (dec.).
Sources & evidence
- ORD record
- ord-bc57f216f3af431486faa0906d1eb494
- Source dataset
- uspto-grants-1984_04
- Patent number
- US04442101
Reaction notes
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