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Amines Bearing Tertiary Substituents by Tandem Enantioselective Carbolithiation–Rearrangement of Vinylureas

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journal contribution
posted on 20.02.2016, 02:36 by Michael Tait, Morgan Donnard, Alberto Minassi, Julien Lefranc, Beatrice Bechi, Giorgio Carbone, Peter O’Brien, Jonathan Clayden
In the presence of (−)-sparteine or a (+)-sparteine surrogate, organolithiums add to N-alkenyl-N′-arylureas to give benzylic organolithiums in an enantioselective manner. Under the influence of DMPU, these organolithiums undergo rearrangement with migration of the N′-aryl ring from N to C, leading to the urea derivatives of enantiomerically enriched amines bearing tertiary substituents. Basic hydrolysis returns the functionalized amine, providing a new synthetic route to compounds with quaternary stereogenic centers bearing nitrogen.