Quinones in asymmetric arylation and biaryl coupling

Quinones are widespread compounds in nature, where they play key roles due to their biological activity. Quinones have proven their usefulness in the field of synthetic chemistry, being excellent oxidants and electrophiles. In this thesis work, two example of efficient exploitment of quinones as electrophiles are presented. In one case, an asymmetric organocatalyzed biaryl couling is presented, a reaction which proceeds with the addition of a nucleophilic naphthol to a substituted electrophilic quinone, followed by rearomatization of the quinone. The reaction is catalyzed by Cinchona alkaloids, such as Quinine, and afforda atropisomer biaryls in excellent yields (>95%) and good enantioselectivity (up to 86% ee, raised to 98% after recrystallization). In the second example, malonates, substituted with differents alkyl side chains, are coupled to electrophiles quinones; the alkylation of the quinone by mean of the malonate is followed by a step of desymmetrization which envolves the interaction of the intermediate with a chiral thiourea, derived from Cinchona alkaloyd. The reaction affords chiral benzofuran-2-ones bearing a quaternary carbon in good yields (up to 95%) and excellent enantioselectivity (up to 92% ee). The thesis is concluded with a study of the reaction of rearomatization of 4-substituted-dihydropyridines to 4-substituted-pyridines atropisomers.