Subtilisin enzymatic resolution

Mugford, P.F., Lait, S.M., Keay, B.A. and Kazlauskas, R.J., Enantiocomplementary enzymatic resolution of the chiral auxiliary c7j,c7j-6-(2,2-dimethylpropanamido)spiro-[4.4]nonan- l-ol and the moleuclar basis for the high enantioselectivity of subtilisin Carlsberg. ChemBioChem, 2004, 5, 980-987. 

Enzymatic Resolution of Ethyl Sulfopropionate 2 with Subtilisin Carlsberg I 389... 

DKR of secondary alcohol is achieved by coupling enzyme-catalyzed resolution with metal-catalyzed racemization. For efficient DKR, these catalyhc reactions must be compatible with each other. In the case of DKR of secondary alcohol with the lipase-ruthenium combinahon, the use of a proper acyl donor (required for enzymatic reaction) is parhcularly crucial because metal catalyst can react with the acyl donor or its deacylated form. Popular vinyl acetate is incompatible with all the ruthenium complexes, while isopropenyl acetate can be used with most monomeric ruthenium complexes. p-Chlorophenyl acetate (PCPA) is the best acyl donor for use with dimeric ruthenium complex 1. On the other hand, reaction temperature is another crucial factor. Many enzymes lose their activities at elevated temperatures. Thus, the racemizahon catalyst should show good catalytic efficiency at room temperature to be combined with these enzymes. One representative example is subtilisin. This enzyme rapidly loses catalytic activities at elevated temperatures and gradually even at ambient temperature. It therefore is compatible with the racemization catalysts 6-9, showing good activities at ambient temperature. In case the racemization catalyst requires an elevated temperature, CALB is the best counterpart. 

Enzymatic Kinetic Resolution of N-Boc-Amino Add-Thioesters Coupled with Base-catalyzed Racemization Recently, a new method leading to the preparation of a number of aryl-glycines of the L-configuration has been published. The method is based on the hydrolysis of N-Boc-amino acid thioesters 15 catalyzed by an industrial preparation of the protease subtilisin (Scheme 13.16) [43]. 

The resolution of ( )-Z/77 7 o-mcthylphcnidate (10) free base by enantioselective enzymatic hydrolysis was first reported by us (Novartis) (Scheme 9).[ ] a-Chy-motrypsin and subtilisin carlsberg exhibited selectivity towards the hydrolysis of the (2/ ,2 / )-enantiomer. 

Thus, an enzymatic reaction with a preference such that the monoacid (R)-2a is generated could be expected from the literature. Indeed, the specificity requirements were met surprisingly well again by Subtilisin Carlsberg, which had already been used in the resolution of racemic 10 (cf. Section 6.2.3.1). The development of this reaction is the main topic of this chapter and will be described in Section 6.3. 

It has been demonstrated that the combination of metal-catalysed racemisation and enzymatic kinetic resolution is a powerful method for the synthesis of optically active compounds from racemic alcohols and amines. There are many metal complexes active for racemisation, but the conditions for enzymatic acylation often limit the application of the metal complexes to DKR. In the case of DKR of alcohols, complementary catalyst systems are now available for the synthesis of both (R)- and (5)-esters. Thus, (R)-esters can be obtained by the combination of an R-selective lipase, such as CAL-B or LPS, and a racemisation catalyst, whereas the use of an A-selective protease, such as subtilisin, at room temperature provides (5)-esters. The DKR of alcohols can be achieved not only for simple alcohols but also for those bearing various additional functional groups. The DKR of alcohols has also been applied to the synthesis of chiral polymers and coupled to tandem reactions, producing various polycyclic compounds. 

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