<i>Cinchona</i> Alkaloid Catalyzed Enantioselective [4 + 2] Annulation of Allenic Esters and <i>in Situ</i> Generated <i>ortho</i>-Quinone Methides: Asymmetric Synthesis of Functionalized Chromans

A novel enantioselective [4 + 2] annulation of the allenoates having a unique positive <i>ortho</i>-effect with <i>in situ</i> generated <i>ortho</i>-quinone methides has been developed under the catalysis of <i>Cinchona</i> alkaloid. This chiral amine-catalyzed reaction provides an alternative route to asymmetric catalytic construction of synthetically interesting, highly functionalized chiral chromans in good to excellent enantioselectivities (up to 97% ee)