Diversity/Target Oriented Synthesis of Complex Molecules via Multi-Component Reactions

The rapid generation of diverse sets of complex molecules can be achieved by employing diversity oriented synthetic strategies in combination with so called complexity generating reactions. Multicomponent reactions (MCRs) have been emerged as an extremely powerful tool in combinatorial chemistry and drug discovery, since it offers significant advantages over conventional linear step syntheses, in terms to improve classical organic reactions, promote new reactions and develop straightforward synthetic routes for bioactive heterocycles [1] and natural products [2]. MCRs are convergent reactions in which three or more starting materials react to form a product, where basically all or most of the atoms contribute to the newly formed product. In MCRs, a product is assembled according to a cascade of elementary chemical reactions. Thus, there is a network of reaction equilibria, which all finally flow into an irreversible step yielding the product. The challenge is to conduct multicomponent reactions in such a way that the network of pre-equilibriated reaction channel into the main product and do not yield side products. The result is clearly dependent on the reaction conditions; solvent, temperature, catalyst, concentration, the kind of starting materials and functional groups. In a true sense, these represent environmentally friendly processes by reducing the number of steps, energy consumption, and waste production. MCRs play an important role in combinatorial chemistry because of its ability to synthesize small drug-like molecules with several degrees of structural diversity. A MCR is defined as three or more different starting materials that react to form a product, where most, if not all of the atoms are incorporated in the final product. This reaction tool allows compound to be synthesized in few steps and usually in a one-pot operation [3]. Another typical benefit from these reactions is simplified purification, because all of the reagents are incorporated into the final product.