The
development of enantioselective desymmetrization of para-quinamines with isocyanates catalyzed by chiral phosphoric
acid is reported. The strategy provides concise access to functionalized
imidazolidin-2-one derivatives in high yields and enantioselectivities
under mild reaction conditions. Remarkably, this reaction could be
performed on a gram scale using 5 mol % catalyst loading and the chiral
imidazolidin-2-one derivatives could be easily transformed into valuable
scaffolds without disturbing the enantiopurity, demonstrating the
synthetic utility of this protocol.
An efficient and environmentally friendly synthetic approach to prepare thiazolidine-2-imine and oxazolidine-2-one derivatives has been developed. Thiazolidine-2-imines are synthesized in good to excellent yields by [3 + 2] annulation of pquinamines with isothiocyanates under catalyst-and solvent-free conditions. Oxazolidine-2-ones are produced in good to excellent yields via [3 + 2] annulation of p-quinamines with CO 2 using triethylenediamine (DABCO) as an organocatalyst. Furthermore, this strategy can be performed on a gram scale and tolerate a wide range of functional groups. Article pubs.acs.org/joc
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