Enzym‐katalysierte Reaktionen, 7. Enantioselektive Veresterung racemischer Cyanhydrine und enantioselektive Hydrolyse oder Umesterung racemischer Cyanhydrinester mittels Lipasen

Abstract

Enzyme‐Catalyzed Reactions, 71). – Enantioselective Esterification of Racemic Cyanohydrins and Enantioselective Hydrolysis or Transesterification of Cyanohydrin Esters by Lipases Pure cyanohydrin enantiomers (S)‐1/(R)‐1 and their O‐acyl derivatives (R)‐3/(S)‐3 are obtained from three different lipasecatalyzed reactions: i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective acylation of racemic cyanohydrins 1, iii) enantioselective transesterification of 3 with primary alcohols. Both the cyanohydrin esters and the free cyanohydrins (which are prone to racemization) are isolated as enantiomers with high optical purity on a preparative scale. Hydrolysis of the racemic butyrates 3b, e with Candida cylindracea lipase and pseudomonas sp. lipase, respectively, for example, affords the free (S)‐cyanohydrins (S)‐2‐hydroxypentanenitril [(S)‐1a] and (S)‐mandelonitrile [(S)‐1b)] in high yield with 97 and 96% ee, respectively. (S)‐1a is obtained with the same optical purity by candida sp. lipase‐catalyzed transesterification of 3b with 1‐octanol.

Camphor-grown Pseudomonas putida, a multifunctional biocatalyst for undertaking Baeyer-Villiger monooxygenase-dependent biotransformations

“…The recently-developed use of the NADH-dependent diketocamphane monooxygenase from (+)-camphor-grown Pseudomonas putida NCIMB 10007 is an interesting departure from the more traditional use of the NADPH-dependent cycloalkanone monooxygenase from cyclohexanol-grown Acinetobacter calcoaceticus NCIMB 9871 because when tested with bicyclo(3.2.0)hept-2-en-6-one as substrate the two oxidative enzymes yield both 2-oxa and 3-oxa lactones that are in each case antipodes (Grogan et al, 1992(Grogan et al, , 1993 (Gunsalus et al, 1971). (Zhou et al, 1983;Ladner et al, 1984;Holland et al, 1985;Keinan al., et 1986;Colonna et al, 1988;Pan et al, 1990;Effenberger et al, 1991 Microorganisms, maintenance and growth. These were as previously described (Grogan et al, 1992).…”

Optically Active Cyanohydrins and Enzyme Catalysis

“…of the free cyanohydrin in the sample can be obtained by acylating with an appropriate acid anhydride in the presence of pyridine and DMAP. The absolute configurations of the products are based on the chiral GLC method, on the retention times of (R)-cyanohydrins obtained through (R)oxynitrilase catalysis and on the literature data about enzymatic enantioselectivities (Effenberger et al, 1991;Inagaki et al, 1992;Kanerva, Kiljunen and Huuhtanen, 1993).…”

“…CCL and lipase PS catalyses have been successfully used in this work and in some previous works (Ekvinakatti et al,1989;Effenberger et al, 1991; Inagaki et al, 1992;Kanerva, Kiljunen and Huuhtanen, 1993) for the enantioselective deacylations of both aliphatic and aromatic acylated compounds (Scheme 2). The enantioselectivities of the lipases are shown in the Schemes.…”

“…The (5)-oxynitrilase catalyzed condensation of HCN with para-substituted (Me, C1 and OH) aromatic aldehydes (e.e. 78,54 and 94 % and yields 61, 87 and 84 % I respectively) cannot compete with the methods which use lipase PS catalysis(Effenberger et al, 1991).For the preparation of aromatic (R)-cyanohydrins (R)-oxynitrilase catalysis is equal to the lipase PS catalyzed deacylation of acylated cyanohydrins as to the high optical purity (Table l), but the chemical yields are often considerably higher in the first-mentioned case. Thus, the (R)-cyanohydrins 6a-8a were Biocatal Biotransformation Downloaded from informahealthcare.com by McMaster University on 10/14/14…”

Enzyme‐Catalyzed Asymmetric Synthesis

“…In a (nondynamic) kinetic resolution, cyanohydrins are acylated in the presence of a lipase very effi ciently, leading to enantiomerically enriched cyanohydrin acetates [7] . In a (nondynamic) kinetic resolution, cyanohydrins are acylated in the presence of a lipase very effi ciently, leading to enantiomerically enriched cyanohydrin acetates [7] .…”