An indispensable source-book for the research scholars working in the field of heterocyclic chemistry especially flavanones, pyrazolines and isoxazolines. This book describes the synthesis of some newly substituted 1, 3-propanedione, 3-aroyl flavanones, 1- substituted 3-5-diaryl - 4aroyl pyrazolines and 1- substituted 3-5-diaryl-4- aroyl isoxazolines. The special feature of the book is that syntheses have been described along with their probable mechanisms. It also covers Physico - chemical studies: The pH- Metric study of Metal-Ligand stability constants of complexes and the spectrophotometric study of complex formation of metal ion complexes. The book also describes antifungal activities of synthesized compounds. The results mentioned in this book are the conclusions made by the author. However, there may be different opinions in this regard.