Catalytic enantioselective 3+2 cycloadditions of azomethine ylides promoted by (S)-DTBM-Segphos∙Cu(I) complex

The catalytic enantioselective 3+2 cycloaddition between azomethine ylides and activated alkenes is one of the most powerful methods for the construction of highly enantioenriched pyrrolidines, an important scaffold in natural products and pharmaceutical chemistry.[1-4] In this work, we report the synthesis of polysubstituted pyrrolidines with high exo- and enantioselectivity employing a chiral complex prepared in situ from copper(I) triflate and (S)-DTBM-Segphos. This chiral complex was the most suitable after reaction optimization between the iminoester in which R1=Ph and MA with different copper(II) and silver(I) salts. The influence of the arene moiety (R1) into iminoester was also evaluated, o-, m-, and p-substituted arenes and heteroarenes afforded excellent enantiomeric excess (ee) of the almost pure exo-diastereoisomer. Other dipolarophiles as TBA, VPS and maleimides were also used and furnished both excellent diastereo- and enantioselectivities. The preparation of iminosugars from these adducts is under investigation in our laboratories.