Lipases - Enzymes for Biocatalytic Asymmetric Synthesis

Introduction

Lipases (triacylglycerol ester hydrolases, EC 3.1.1.3) are found in most organisms and are known to catalyze the hydrolysis of triglycerides in vivo. [1] [2] They are some of the most studied and used biocatalysts in organic synthesis today. The versatility and popularity of lipases is attributed to their high catalytic efficiency on a broad range of substrates, combined with high regioselectivity and chiral recognition, [2] their high stability in organic solvents and at elevated temperatures, [2] [3] the reversibility of their mode of action into ester synthesis, [2] [4] their non-toxic and environmentally friendly nature, [5] and finally, their low cost.

Lipases from many different species have been isolated and are commercially available in different preparations such as crude powders, lyophilisates, or immobilized on solid particles or resins. Many are of microbial origin, and advances in biotechnology have allowed production of ­lipases on a multi-ton scale using recombinant hosts. [2]

In practice, lipases are very easy to handle and use. The principal reactions catalyzed by the enzymes are ester ­hydrolysis or synthesis, typically of acetates (Scheme 1). Hydrolysis is usually performed in a biphasic system ­consisting of an aqueous buffer and an organic solvent. Esterification is accomplished in an organic solvent with an irreversible acyl donor, [4] such as the enol ester vinyl ­acetate. The enzyme is conveniently removed by filtration during work-up. The inherent chirality of the enzyme ­dictates a stereopreference of the reactions which can be exploited for asymmetric synthesis.

Scheme 1 Principle reactions in synthesis catalyzed by lipases.

The applications of lipases in synthesis are diverse, and include resolution of racemates, [6] hybrid metal-enzyme catalyzed dynamic kinetic resolution, [7] desymmetrizations of prochiral or meso substrates [8] and regioselective protective group manipulations. [9a] [b]

References

• 1 Reetz MT. Curr. Opin. Chem. Biol.  2002,  6:  145 
• 2 Schmid RD. Verger R. Angew. Chem. Int. Ed.  1998,  37:  1608 
• 3 Klibanov AM. Nature  2001,  409:  241 
• 4 Hanefeld U. Org. Biomol. Chem.  2003,  1:  2405 
• 5 Koeller KM. Wong C.-H. Nature  2001,  409:  232 
• 6 Ghanem A. Aboul-Enein HY. Tetrahedron: Asymmetry  2004,  15:  3331 
• 7 Pàmies O. Bäckvall J.-E. Chem. Rev.  2003,  103:  3247 
• 8 Garcia-Urdiales E. Alfonso I. Gotor V. Chem. Rev.  2005,  105:  313 
• 9a Kadereit D. Waldmann H. Chem. Rev.  2001,  101:  3367 
• 9b La Ferla B. Monatsh. Chem.  2002,  133:  351 
• 11 Sundby E. Holt J. Vik A. Anthonsen T. Eur. J. Org. Chem.  2004,  1239 
• 12a Kamal A. Sandbhor M. Ramana KV. Tetrahedron: Asymmetry  2002,  13:  815 
• 12b Kamal A. Sandbhor M. Shaik AA. Bioorg. Med. Chem. Lett.  2004,  14:  4581 
• 13 Yamagishi T. Miyamae T. Yokomatsu T. Shibuya S. Tetrahedron Lett.  2004,  45:  6713 
• 14 Gonçalves PML. Roberts SM. Wan PWH. Tetrahedron  2004,  60:  927 
• 15 Martín-Matute B. Edin M. Bogár K. Bäckvall J.-E. Angew. Chem. Int. Ed.  2004,  43:  6535 
• 16 Matsumoto T. Konegawa T. Nakamura T. Suzuki K. Synlett  2002,  122 
• 17 Neri C. Williams JMJ. Adv. Synth. Catal.  2003,  345:  835 

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Lipase enzymes are abbreviated with respect to the species of origin. For the exact preparation and trade name, please see the original reference.