The first part of this book describes the detailed mechanism of ruthenium catalyzed nucleophilic addition to terminal alkynes with the aim of understanding the key factors controlling the regio- and stereoselectivity of product formation. These types of reactions provide excellent methodologies for the synthesis of enamides and enol-esters. The main challenge of this method arises due to formation of product mixture, Markovnikov and anti-Markovnikov E- or Z- products. Control of regio- and stereoselectivity by modulating the electronic and steric environment along with solvent effect is nicely discussed in this part. The second part deals with the metal free asymmetric transformations and remarkable chemistry of main group radical species. This part also offers the reader to learn how to use modern theoretical techniques to predict the reactivity and product selectivity in terms of ground electronic structure and bonding parameters.