Chalcogen-Bonding Catalyzed In Situ Trityl Cation Activation for C—C Bond Forming Reactions

Abstract

In this work, the use of chalcogen bonding for the catalytic activation of trityl cation by chloride abstraction from bench stable trityl chloride and further application in C—C bond forming reactions is reported. In particular, telluronium salts bearing noncoordinative counter anions such as BAr^F₂₄ proved highly efficient. Thus, low catalyst loading of 1 mol% allows for the trapping of the in situ generated trityl cation in a Friedel–Crafts reaction, as well as its use as catalyst in the carbonyl-ene cyclization of citronellal or as hydride-type oxidant in diastereoselective C—H functionalization/cyclization of tetrahydroisoquinoline derivatives. A new family of chiral chalcogen–triazolium salts presenting the chirality in the central backbone was also designed and employed in the C—H functionalization reaction, slightly outperforming hydrogen and halogen bonding activation. Although no appreciable chirality transfer has been achieved so far, those simple and modular structures might open new possibilities toward enantioselective chalcogen catalysis.