Prochiral diols, enantioselective acylation

Figure 9.6 Enantioselective acylation of prochiral diols 16a,b in continuous-flow lipase-filled PBR.

Other similar lipase/esterase resolution processes have been developed such as the use of Bacillus that esterase to produce the substituted propanoic acids that are precursors of non-steroidal anti-inflammatory drags, snch as naproxen and ibuprofen etc., and the formation of chiral amines by Celgene. Other methods start from prochiral precursors and have the advantage that enantioselective synthesis allows the production of particular isomers in yields approaching 100%, rather than the 50% yields characteristic of resolution processes. For instance Hoechst have patented the production of enantiomers using Pseudomonas fluorescens lipase to either acylate diols or hydrolyse diacetate esters. 

Because of the results with numerous prochiral diesters and diols, which have been subjected successfully to hydrolase-catalyzed enantioselective hydrolysis and acylation, respectively, and because of the desire to predict the sense of the asymmetric induction in the conversion of a new substrate, active-site or substrate models have been developed for the hydrolases pig liver esterase171 731, pig pancreas... 

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