1H-Pyrazole-5-amino-3-carboxylic acid

5-Amino-1H-pyrazole-3-carboxylic acid (CAS 124004-31-5) is a high-purity heterocyclic building block widely used in pharmaceutical intermediates and medicinal chemistry . This functionalized pyrazole derivative features two orthogonal reactive handles: a C5-amino group for electrophilic substitution or cyclization, and a C3-carboxylic acid for direct amide coupling or salt formation—eliminating the need for prior hydrolysis steps required with ester analogs . The electron-rich 1H-pyrazole core, combined with the ortho-like arrangement of amino and carboxyl functionalities, enables efficient construction of fused heterocyclic systems including pyrazolo[1,5-a]pyrimidines and pyrazolo[3,4-d]pyridazines . Key applications include the synthesis of kinase inhibitors targeting ATP-binding pockets, anti-inflammatory agents (including P2Y14 receptor antagonists) , and agrochemical active ingredients. Recent research has demonstrated its utility in developing potent GPR109b agonists for metabolic disorders  and anti-inflammatory compounds with improved solubility and bioavailability . Manufactured under controlled conditions, this intermediate supports drug discovery programs requiring direct access to the acid pharmacophore for salt formation, bioisosteric replacement of histidine, or as a precursor for synthesizing corresponding methyl/ethyl esters under controlled conditions.