Biocatalysis offers an alternative approach to conventional chemical processes for the production of single-isomer chiral drugs. Lipases are one of the most used enzymes in the synthesis of enantiomerically pure intermediates. The use of this type of enzyme is mainly due to the characteristics of their regio-, chemo- and enantioselectivity in the resolution process of racemates, without the use of cofactors. Moreover, this class of enzymes has generally excellent stability in the presence of organic solvents, facilitating the solubility of the organic substrate to be modified. Further improvements and new applications have been achieved in the syntheses of biologically active compounds catalyzed by lipases. This review critically reports and discusses examples from recent literature (2007 to mid-2015), concerning the synthesis of enantiomerically pure active pharmaceutical ingredients (APIs) and their intermediates in which the key step involves the action of a lipase.

No abstract

No abstract

The lipase kinetic resolution (KR) of aryloxy-propan-2-yl acetates, via hydrolysis, produced enantiomerically pure/enantioenriched mexiletine intermediates and analogs. Racemic acetates rac-1-(2,6-dimethylphenoxy)propan-2-yl acetate (rac-5a), rac-1-(2,4-dimethylphenoxy)propan-2-yl acetate (rac-5b), rac-1-(o-tolyloxy)propan-2-yl acetate (rac-5c) and rac-1-(naphthalen-1-yloxy)propan-2-yl acetate (rac-5d) were used as substrates. A preliminary screening (24 h, phosphate buffer pH 7.0 with 20% acetonitrile as co-solvent, 30 °C and enzyme: substrate ratio of 2:1, m:m) was carried out with twelve lipases using acetate 5a as substrate. Two enzymes stood out in the KR of 5a, the Amano AK lipase from Pseudomonas fluorescens and lipase from Thermomyces lanuginosus (TLL) immobilized on Immobead 150. Under these conditions, both the (R)-1-(2,6-dimethylphenoxy)propan-2-ol [(R)-4a] and the remaining (S)-1-(2,6-dimethylphenoxy)propan-2-yl acetate [(S)-5a] were obtained with enantiomeric excess (ee) > 99%, 50% conversion and enantiomeric ratio (E) > 200. The KR study was expanded to racemic acetates 5b-d, leading to the corresponding chiral remaining acetates with ≥ 95% ee, and the alcohols 4b-d with ≥ 98% ee, and conversion values close to 50%. The best conditions for KRs of rac-5b-d involved the use of lipase from P. fluorescens or TLL immobilized on Immobead 150, 24 or 48 h and 30 °C. These intermediates had their absolute configurations determined using 1H NMR spectroscopy (Mosher’s method), showing that the KRs of these acetates obeyed the Kazlauskas’ rule. Molecular docking studies corroborated the experimental results, indicating a preference for the hydrolysis of (R)-5a-d.