Process for the preparation of pyrazoles

This invention relates to a novel process for the preparation of pyrazoles. In particular the present invention relates to a novel process for the preparation of pyrazole intermediates useful in the synthesis of 4-alkylpiperazinylsulfonylphenyl- and 4-alkylpiperazinylsulfonyl pyridinyl-dihydropyrazolo[4,3-d]pyrimidin-7-one derivatives which are potent and selective cGMP PDE inhibitors. A "one-pot" process is described herein for the production of pyrazole compounds of general formula (II) comprising the steps of reacting a compound of general formula (III) with an acylating agent in the presence of a base and an optional activating agent followed by the addition of a hydrazine compound in situ.