Sulfur, nitrogen and oxygen based reagents have become an important part of the store of synthetic chemists. The chemistry of sulfur, nitrogen and oxygen containing compounds and their reactivity, together with an understanding of their mechanisms, is an important part of the modern organic chemistry. This book is concerned with the chemistry of organic compounds possessing at least one C-S, N-C, S-O and S-N bonds. The overall approach is a compromise between the preparation, isolation and properties of the some topics of pyrazolones, pyrazolines, thiazolidones, triazoles, imidazoles, pyrrolidinones, pyridines, pyrimidines, indolin-2-ones, azabenzanthrones and 1,2-diazepine compounds and a discussion of their applications in synthesis. Studies have been carried out on the photochemical behavior of imperatorin, including photolysis and sigmatropic effects in different solvents and photodimerisation. Work has been carried out on the synthesis and dyeing performance of several pyrazolin-5-ones thiazolidines on polyester fibres. Much has been carried out on the isolation and structure elucidation of plants of the family Composite.