This book deals with synthesis of some novel aza heterocyclic compounds using newer methodologies. Because of the vast pharmaceutical importances, the synthesis of aza heterocyclic compounds becomes an important field of research. Development of new synthetic strategies which includes green approaches, easy reaction condition, good yield of product, short reaction time etc have been reported in this book. Besides, use of conjugated carbonyl compounds as an effective substrate towards the synthesis of aza-heterocycles has also been cited here. This book reports some new reaction strategies towards synthesis of piperazines, pyridine, pyrimidine, indole and pyridone derivatives using steroidal and non-steroidal conjugated carbonyl compounds as a substrate under improved reaction condition. It also focuses on the use of urea as an efficient source of ammonia. The content mainly includes different new and novel methodologies leading to aza heterocycles, spectral datas of different analytical techniques, use of conjugated carbonyl compounds as an efficient substrate for aza heterocyclic synthesis along with the exploration of urea as a safe and efficient source for generating ammonia.