Switching Diastereoselectivity in Catalytic Enantioselective (3+2) Cycloadditions of Azomethine Ylides Promoted by Metal Salts and Privileged Segphos-Derived Ligands

Catalytic enantioselective 1,3-dipolar cycloaddition between imino esters and electrophilic alkenes, employing chiral metal complexes derived from copper(I) and silver(I) salts and (S)-DM- or (S)-DTBM-Segphos as ligands produces diastereodivergently exo- or endo-cycloadducts, respectively. The effect of the functional group of the dipolarophile and the fine tuning of the catalyst plays an important role in promoting reverse diastereoselectivities. The origins of experimentally observed enantioselectivity and diastereoselectivity data, as well as the origin of the observed switched endo/exo ratios, are also explained by means of density functional theory calculations.The authors gratefully acknowledge the financial support from CAPES (Brazil), the Spanish Ministerio de Ciencia, Innovación y Universidades (projects CTQ2013-43446-P, CTQ2016-81893REDT and CTQ2014-51912-REDC), the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU) (projects CTQ2016-76782-P, CTQ2016-80375-P and CTQ2016-81797-REDC), the Generalitat Valenciana (PROMETEOII/2014/017), the Gobierno Vasco/Eusko Jaurlaritza (GV/EJ, Grant IT673-13), and the University of Alicante. G.S.C. acknowledges CAPES (Brazil) for the fellowship (Process CSF-PVE-S-88887.127574/2016-00). O.L. gratefully acknowledges UPV/EHU for her postdoctoral grant