Catalytic Diastereo- and Enantioselective Synthesis of 2-Imidazolinones (original) (raw)

Chiral cyclic ureas (2-imidazolinones) were prepared by the reaction of nitrones and isocyanoacetate esters using a multicatalytic system that combines a bifunctional Brønsted base-squaramide organocatalyst and Ag + as Lewis acid. The reaction could be achieved with a range of nitrones derived from aryl-and cycloalkylaldehydes with moderate diastereo-and good enantioselectivity. A plausible mechanism involving an initial formal [3+3] cycloaddition of the nitrone and isocyanoacetate ester, followed by rearrangement to an aminoisocyanate and cyclization to the imidazolinone is proposed.