Synthesis of 4-aryl-1H-pyrazoles by Suzuki-Miyaura cross coupling reaction between 4-bromo-1H-1-tritylpyrazole and arylboronic acids

A general procedure for the synthesis of 4-aryl-1H-pyrazoles by the Suzuki-Miyaura cross coupling reaction between 4-bromo-1H-1-tritylpyrazole and commercially available arylboronic acids was developed. Using this procedure, a direct synthesis of 4-aryl-1H-pyrazoles possessing functional groups, such as hydroxyl, nitro, and amino groups, on the aryl ring was realized. Those molecules could not be prepared by our previous synthesis of 4-aryl-1H-pyrazoles via the Kumada cross coupling reaction.