3-Chloro-1-(pyridine-3-yl)-1H-pyrazole-5-carboxylic acid hydrochloride → 3-(3-chloro-1H-pyrazol-1-yl)pyridine
Reaction equation
Cl.[Cl:2][C:3]1[CH:7]=[C:6](C(O)=O)[N:5]([C:11]2[CH:12]=[N:13][CH:14]=[CH:15][CH:16]=2)[N:4]=1>[Cu]=O.CN(C)C=O>[Cl:2][C:3]1[CH:7]=[CH:6][N:5]([C:11]2[CH:12]=[N:13][CH:14]=[CH:15][CH:16]=2)[N:4]=1Participants
4
Reactant 1
Product 1
Reagents, catalysts & solvents 2
Procedure
In step e of Scheme 4, 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylic acid hydrochloride (6e) is decarboxylated in the presence of copper (II) oxide in polar solvents such as N,N-dimethylformamide at temperatures from about 80° C. to about 140° C. to yield 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b). It was surprisingly discovered that this decarboxylation only occurs in the presence of copper (II) oxide. Several known decarboxylation agents from the literature such as, for example, hydrochloric acid (See alternate synthetic route, Example 14), sulfuric acid, and palladium (II) trifluoroacetate/trifluoroacetic acid (See “CE-5”) did not yield the desired product.
Sources & evidence
- ORD record
- ord-eb47d41698154f91ba351df348597ba6
- Source dataset
- uspto-grants-2016_02
- Patent number
- US09255083B2
Reaction notes
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