Recent advances in the synthesis of polysubstituted 3-pyrazolidinones

An account of recent developments in the field of 3-pyrazolidinone chemistry is given with special focus on the synthesis and transformations of 5-substituted 4-benzyloxycarbonylamino-3pyrazolidinones, pyrazolo[1,2-a]pyrazole-based peptide analogues, and tetrahydropyrazolo-[1,5-c]pyrimidine-2,7-diones. In terms of practical application, polyfunctionalized 3-pyrazolidinones as 'aza-deoxa' analogues of cycloserine, peptide mimetics based on 3-amino-2-oxo-1,5diazabicyclo[3.3.0]octane-7-carboxylic acid, and 1,6-disubstituted tetrahydropyrazolo[1,5-c]pyrimidine-2,7-diones as the first representatives of a novel saturated heterocyclic system were prepared by these newly developed synthetic methods.