Asymmetry from an Industrial Scale Perspective

As mentioned previously, the field of asymmetric synthesis began to advance rapidly in the late 1960s. However, the important prior contribution of Nakamura [18] should be noted. In 1941 he demonstrated that a chiral auxihary (an acid) could be used to alter the surface of a heterogeneous catalyst (Pt black) to successfully reduce an imine bond (C=N) in 18% ee. Other Japanese workers built on these ideas and were able to develop two commercially viable catalytic systems 

Space limitations do not allow every procedure of importance to be mentioned, but one that should be included is the production process for (S)-metolachlor, a herbicide marketed under fhe trade name Dual Magnum by Syngenta (formerly Ciba-Geigy). Volume-wise, this presently constitutes fhe largest production process of any kind applying an asymmetric reaction, with its aimual capacity of more than 10000 tonnes [35]. The efficiency obtained in fhis method based on a planar 

Neurospora crassa (whole cell system NADH provides reducing power) 

To complete the list of frequently encountered chiral ligands that have demonstrated their versatility on the production scale, the DuPHOS [36] and salen [37] motifs should be mentioned. Members of the former class have shown excellent 

Of course, the literature on the subject of asymmetric synthesis is so vast that a comprehensive coverage is far beyond the scope of this chapter. Instead, a few recent relevant sources are given for those readers interested in gaining a deeper and broader insight [40-43]. 

---