The Application of Enzymes in the Synthesis of Amino Acids, Peptides and Carbohydrates

Abstract

Enzymatic transformations have recently assumed great importance in the synthesis of enantiomerically pure amino acids and carbohydrates, particularly as the requirement for efficient methods in catalytic asymmetric synthesis increases. A large number of enzymes, that catalyse a wide range of different synthetic transformations, have been identified and are J currently being applied in many laboratories including our own. This Chapter will focus on recent work from the Edinburgh group and will address the application of those enzymes that catalyse the (i) hydrolysis of esters (ii) the ring-opening of oxazolones in. organic solvents (iii) the hydrolysis and synthesis of glycosides (iv) the asymmetric synthesis of carbon-carbon bonds. Emphasis will be placed on the development of protocols for carrying out these biocatalytic transformations on a medium to large scale. The use of .enzymes in the preparation of amino acid and carbohydrate derivatives will be illustrated by the syntheses of biologically active pharmaceutical intermediates and selected target molecules such as morphine-6-glucuronide, L-tert-leucine, pseudopeptides, and novel glycosidase inhibitors. Finally, a brief section on the use of enzymes in solid -phase synthesis will be included in which it will be shown that enzymes can be used not only to carry out selective transformations on a solid support, but also to act as highly selective reagents for the cleavage of the products by the design of appropriate enzyme­cleavable linker systems.