Highly Z-Selective Synthesis of Highly Substituted 1,3-Oxathiolane-2-imines via TfOH-Catalyzed Formal 3+2 Cycloaddition of Donor-Acceptor Oxiranes and Isothiocyanates

摘要

TfOH-catalyzed [3+2] cycloaddition of donor-acceptor oxiranes with isothiocyanates via chemoselective C-O bond breakage of D-A oxiranes was developed under metal- and additive-free conditions. This method providing a facile access to a diverse range of highly substituted 1,3-oxathiolane-2-imines in good to excellent yields and with high Z-selectivity and excellent functional group tolerance. In addition, the established protocol can be easily scaled up to gram level in excellent yield. Furthermore, transformation of cycloadduct into 1,3-oxathiolane-2-one by acid hydrolysis of the imino group is easily achieved in moderate yield.