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Pyrazole‐4‐carboxylic Acids from Vanadium‐catalyzed Chemical Transformation of Pyrazole‐4‐carbaldehydes

“…In this paper, we report a convenient synthesis of pyrazole-4-carboxylic acids (2a-p) from pyrazole-4carbaldehydes (1a-p) [4,26,[29][30][31][32] using vanadium catalyst in the presence of 30% H 2 O 2 in acetonitrile (Scheme 1).…”

“…The 4‐formylpyrazoles, that is, 1,3‐diphenyl‐1 H ‐pyrazole‐4‐carbaldehyde ( 2a ), 3‐(4‐chlorophenyl)‐1‐phenyl‐1 H ‐pyrazole‐4‐carbaldehyde ( 2b ), 3‐(4‐bromophenyl)‐1‐phenyl‐1 H ‐pyrazole‐4‐carbaldehyde ( 2c ), 3‐(4‐ethylphenyl)‐1‐phenyl‐1 H ‐pyrazole‐4‐carbaldehyde ( 2d ), 3‐([1,1′‐biphenyl]‐4‐yl)‐1‐phenyl‐1 H ‐pyrazole‐4‐carbaldehyde ( 2e ), 4‐(4‐formyl‐3‐phenyl‐1 H ‐pyrazol‐1‐yl)benzenesulfonamide ( 2f ), 4‐(4‐formyl‐3‐( p ‐tolyl)‐1 H ‐pyrazol‐1‐yl)benzenesulfonamide ( 2g ), 4‐(4‐formyl‐3‐(4‐methoxyphenyl)‐1 H ‐pyrazol‐1‐yl)benzenesulfonamide ( 2h ), and 4‐(3‐(4‐chlorophenyl)‐4‐formyl‐1 H ‐pyrazol‐1‐yl)benzenesulfonamide ( 2i ), were prepared by the reporting procedures .…”

“…, and 4-(3-(4-chlorophenyl)-4-formyl-1H-pyrazol-1-yl) benzenesulfonamide (2i), were prepared by the reporting procedures [4,26].…”

Lonazolac analogues: molecular modeling, synthesis, and in vivo anti-inflammatory activity

“…Scheme 2 describes the synthesis of pyrazoles-4-carboxylic acids 5a-d from the corresponding aldehydes 3a-d by the oxidation using potassium permanganate in aqueous pyridine (Bratenko et al, 2001). The carboxylic acid moiety was linked to anthranilamide to form the amides 6a-d and to salicylamide to form the esters 7a-d using mixed anhydride method.…”

“…The acid chlorides were prepared according to Bratenko et al (2001) using thionyl chloride in dry toluene. The mixed anhydride method failed to prepare compounds 8a-c directly from the carboxylic acids 5a-c (Scheme 2).…”