Synthesis of Functionalized Thiazolidin-2-imine and Oxazolidin-2-one Derivatives from p-Quinamines via [3 + 2] Annulation of Isothiocyanates and CO2

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 p-quinamines 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 CO2 using triethylenediamine (DABCO) as an organocatalyst. Furthermore, this strategy can be performed on a gram scale and tolerate a wide range of functional groups.