Acylase, artificial

Miller s biomimetic approach inspired Ishihara [234] to develop a minimal artificial acylase for the KR of mono-protected cw-l,2-diols and A-acylated 1,2-amino alcohols. Derived from (S)-histidine, Ishihara s organocatalyst contains only one stereogenic centre and incorporates a sulfonamide linkage in place of a polypeptide chain to allow the NH group to engage as an H-bond donor with the substrates (Fig. 13) [234]. 

Enantioselective acylation of amine and hydrolysis of amide are widely studied. These reactions are catalyzed by acylases, amidases and lipases. Some examples are shown in Figure 21.22 Aspartame, artificial sweetener, is synthesized by a protease, thermolysin (Figure 21(a)).22a In this reaction, the L-enantiomer of racemic phenylalanine methyl ester reacted specifically with the a-carboxyl group of N-protected L-aspartate. Both the separation of the enantiomers of the phenylalanine and the protection of the y-carboxyl group of the L-aspartate were unnecessary, which simplified the synthesis. 

Design of highly functional small-molecule catalysts and related reactions based on acid-base combination chemistry (particularly, synthesis of oxazolines and thiazolines and L-histidine-derived sulfonamide as a minimal artificial acylase for the kinetic resolution of racemic alcohols) 07SL686. 

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