Pyrazolidine-3,5-diones, their synthesis and pharmacological importance

CONTENTS
I. Introduction 535
II. Methods of preparation 536
III. Tautomerism in the pyrazolidine-3,5-dione series 539
IV. Stability of the pyrazolidine-3,5-dione ring 541
V. Electrophilic and nucleophilic substitution reactions 542
VI. The character of the pyrazolidine-3,5-dione ring 546
VII. Applications of pyrazolidine-3,5-diones 546