Bifunctional Chiral Quaternary Ammonium Salt Catalysts: A Rapidly Emerging Class of Powerful Asymmetric Catalysts

摘要: Chiral quaternary ammonium salt catalysts have emerged as one of the outstanding catalytic principles over last decades. Their ability to activate nucleophiles in a noncovalent fashion makes them unique. However, years it has become obvious that variety difficult transformations activation and control alone does not result sufficient selectivities, same holds true for sole electrophiles by other motifs. Thus, use bifunctional most promising strategies carry out demanding reactions highly stereoselective under mild reaction conditions, many these are possible using methods. This review will highlight some impressive recent examples this field compare performances with those commonly employed ones.