An effective and general method for the highly regioselective synthesis of 1-phenylpyrazoles from beta-enaminoketoesters, tandem Blaise-acylation adducts.

An effective and general route for the regioselective synthesis of 1-phenylpyrazoles has been developed from beta-enaminoketoesters prepared by tandem Blaise-acylation. This method is applicable to a very broad range of substrates, generating a diverse set of 3-aryl-5-alkyl, 3-alkyl-5-aryl, 3,5-diaryl, and 3,5-dialkyl substituted pyrazoles regioselectively. The dichotomous regioselective synthesis of isotopically discriminated 3-CD(3)-5-CH(3) and 3-CH(3)-5-CD(3) substituted pyrazoles showcases the power of this protocol.