Microwave Assisted Organic Synthesis (MAOS) is a fast development area in synthetic organic chemistry. The use of microwave irradiation to carry out chemical synthesis is an upcoming field of research and is a major break- through in synthetic methodology. The book deals with microwave assisted O – alkylation and acylation of 4 – Hydroxy Coumarin, 7 – Hydroxy – 4 – methyl Coumarin and N – alkylation of Benzanilide, p – toluene sulphonamide, Benzimidazole, 3 ,4 – dihydropyrimidin -2 (1H) ones, and 2, 4, 5 triaryl imidazole in presence of Phase Transfer Catalyst. Many of them display important pharmacological effects, like analgesic, anti-arthritis, anti-inflammatory, anti-pyretic, anti-bacterial, anti-viral, anti-cancer with antifungal action properties. Data presented in the book should be useful to postgraduate and research students of Chemistry, Medicinal Chemistry, Nanotechnology, Waste Management & Environmental Sciences.