1-​(6-​Amino-​9H-​purin-​2-​yl)​-1H-​pyrazole-​4-​carboxylic Acid Ethyl Ester is an intermediate in synthesizing 1-(6-Amino-9H-purin-2-yl)-N-methyl-1H-pyrazole-4-carboxamide (A629440), it is used in the synthetic preparation of regadenoson and intermediates by using cyclocondensation, amidation and condensation as the key steps.