Phosphonium Salts in Asymmetric Catalysis: A Journey in a Decade's Extensive Research Work

The first report on a phosphonium salt as an asymmetric catalyst was published in 1997, and thereafter this area of research remained fairly dormant for almost a decade. However, the second decade (2007–2017) has recorded a significant growth in the published literature and it has now emerged as a hot topic of research. The use of phosphonium salts as a phase-transfer catalyst has gained momentum in recent years due to their ease of availability and simple preparation technique. Most of these asymmetric phosphonium salts are derived from readily available starting materials like chiral amino acids and binaphthyl rings. With a simple modification in the basic core of these moieties, they can be used to execute a number of enantioselective organic transformations. This review presents a comprehensive overview of the historical development of catalyst design, with its necessary modification and applications in selective organic transformations. (Figure presented.).