In drug designing programs an essential component of the search for new leadings is the synthesis of molecules, which is a novel yet, resembles known biologically active molecules by virtue of the presence of critical structural features. Certain small heterocyclic molecules act as highly functionalized scaffolds and are known pharmacophores of a number of biologically active and medicinally useful molecules. Numerous heterocyclic derivatives have received considerable attention because of their diverse biological activity. Pyrazoles and their reduced forms pyrazolines and Iso-oxazoline are well known nitrogen containing heterocyclic compounds and various procedures have been developed for their synthesis. The interest of scientists in such compounds has been stimulated by their various promising pharmacological properties and comparison in methods of synthesis. This book will serve as reference materials for many researchers working in the field of Organic Chemistry, Medicinal Chemistry and Pharmaceutical Chemistry.