Optically Active Cyanohydrins and Enzyme Catalysis

Abstract

The possibilities for the preparation of optically active aliphatic and puru-substituted aromatic cyanohydrins (X-CJI&H(OH)CN) by lipase catalysis in organic solvents has been studied. Pseudomonus cepacia lipase catalyzed deacylation and acylation result in acylated aromatic (R)and Q-cyanohydrins, respectively, with high optical purity (mostly e.e. > 95 46). A convenient access to increase the chemical yield of acylated (S)-cyanohydrins is to combine the basecatalyzed in situ racemization of the less reactive (@-counterpart with a kinetic resolution. The nature of the puru-substituent has not an effect on the enantioselectivity of lipase PS catalysis.In the Cundida cylindruceu lipase catalyzed deacylation, the optical purity of the less reactive (9enantiomer is high (e.e. > 95 96) in the case of the aromatic compounds with electrondonating substituents X. PPL catalysis can be used to acylate aliphatic cyanohydrins, but it is not possible to use the in situ racemization of the less reactive (R)-cyanohydrin owing to the enantiomeric stability of most aliphatic compounds studied. KEY WORDSPorcine pancreatic lipase, Cundidu cyfindracea lipase, Pseudomonus cepaciu lipase, enzymatic transeskrification, cyanohydrin. Biocatal Biotransformation Downloaded from informahealthcare.com by McMaster University on 10/14/14 For personal use only.

Pseudomonas

“…This seems more likely to be the case in P. aeruginosa. Also, the fact that P. aeruginosa is an Kiener, 1992;Wubbolts et al, 1995 Britton andMarkovetz, 1977;Forney and Markovetz, 1969McIntire et al, 1984Reeve et ai., 1989Boyd et al, 1991Watanabe et al, 1987a Allenza et ai., 1991 Rhee et ai., Evans et al, 1987Marquardt et al, 1988 Chan and Salazar, 1991; Krell and Rasor, 1993;Mitsuda et al, 1991 Reviewed in Drauz and Waldmann, 1995 Jaeger and Wohlfarth, 1993;Kanerva et al, 1994;Soberonchavez and Palmeros, 1994Hou, 1993Francalanci et al, 1993Kelly and Fogarty, 1983Amemura and Futai, 1992Jacobs et al, 1991Warhurst and…”

“…Optically active cyanohydrins are synthons needed to produce chiral a-amino acids, aldehydes, and amino alcohols (review : Faber, 1995). Both chiral synthons are industrially produced in a lipase-catalyzed resolution process starting from racemic halohydrins and cyanohydrins, re,spectively (Inagaki et al, 1992;Kanerva et al, 1994;Kutsuki et al, 1986).…”

Biocatalytic enantioselective preparation of phenothiazine-based cyanohydrin acetates: kinetic and dynamic kinetic resolution

“…The proposal is based on the previously found selectivity of CAL-A and lipase PS for the acylation of structurally different phenyl-and furanbased cyanohydrins. [7][8][9]15 2. Results and discussion…”

“…15 Slightly modified lipase-catalyzed methods were previously optimized for the preparation of a number of (S)-phenyl-, (R)-furylbenzotiazol-and (R)-phenylfuran-based cyanohydrin esters. [7][8][9] The potential of lipases 7,15 as simple and economical dynamic kinetic resolution catalysts have been almost forgotten in the flush of the glorious development of oxynitrilase enzymes for the production of cyanohydrin enantiomers. 3,4 We now intend to describe the work where (C)-10-alkylphenothiazin-3-ylhydroxyacetonitrile acetates 3a-e have been prepared through the lipase-catalyzed onepot procedure from the corresponding aldehyde (Scheme 1).…”

“…This is in accordance with the more general proposal that oxynitrilases dislike polycyclic aldehydes. 5 The enantioselective acylation of racemic cyanohydrins [5][6][7][8][9][10] and the enantioselective alcoholysis of racemic cyanohydrin esters 6,7,9,[11][12][13][14] in organic solvents have been widely used in the presence of a suitable lipase. The main disadvantages of the traditional resolution method are, however, the maximum 50% theoretical yield of one enantiomer and the dependence of enantiomeric excess (ee) on the conversion of a reaction.…”