\ Metal-free domino one-pot protocols for quinoline synthesis

Quinoline is one of the most widely investigated scaffolds by synthetic chemists because of its medicinal importance. A wide range of metal-catalyzed, metal-free, multi-step or domino one-pot protocols are reported in the literature for construction of this scaffold. Several reviews have appeared on synthetic aspects of this scaffold, however there is no focused review on metal-free domino one-pot protocols. Domino one-pot protocols offer an opportunity to access highly functionalized final products from simple starting materials. Because of this unique feature of domino protocols, in recent years their utility for generation of molecular libraries has been widely appreciated. In this review, all contributions till March 2015 are surveyed with particular emphasis on metal-free domino reactions for quinoline ring construction and are discussed herein along with mechanistic aspects.