Bakers yeast, reduction with

K Nakamura, YKawai, A Ohno. A novel method to synthesize (L)-(3-hydroxyl esters by the reduction with bakers yeast. Tetrahedron Lett 267-270, 1990. 

Nakamura, K., Kawai, Y., Nakajima, N., and Ohno, A. 1991. Stereochemical control of microbial reduction. 17. A method for controlling the enantioselectivity of reduction with bakers yeast. J. Org. Chem., 56,4778-4783. 

A route to the key synthon (47 ,67 )-4-hydroxy-2,2,6-trimethylcyclo-hexanone had previously been developed by Leuenberger et al. 124) starting from the readily available isophorone. The chiral centre was introduced by enantioselective reduction with bakers yeast, and regio-selective reduction of one keto group was achieved by chemical reduction with nickel catalyst or by triisobutylaluminium under conditions where the desired trans diastereomer was the major product. 

Scheme 3.29 Additives in the enzymatic reduction with bakers yeast.

So far only two groups have reported details of the use of ionic liquids with wholecell systems (Entries 3 and 4) [31, 32]. In both cases, [BMIM][PF(3] was used in a two-phase system as substrate reservoir and/or for in situ removal of the product formed, thereby increasing the catalyst productivity. Scheme 8.3-1 shows the reduction of ketones with bakers yeast in the [BMIM][PF(3]/water system. 

Bertau, M. and Burli, M. (2000) Enantioselective microbial reduction with baker s yeast on an industrial scale. Chimia, 54 (9), 503-507. 

Enzyme reduction with Baker s yeast and enantioselective rule... 

Figure 10.19 Enantioselective ketone reduction with baker s yeast in an ionic liquid...

K Nakamura, Y Kawai, T Miyai, A Ohno. Stereochemical control in diastereoselec-tive reduction with baker s yeast. Tetrahedron Lett 3631-3632, 1990. 

K Ishihara, N Nakajima, S Tsuboi, M Utaka. Asymmetric reduction of l-acetoxy-2-alkanones with bakers yeast purification and characterization of a-acetoxy ketone reductase. Bull Chem Soc Jpn 67 3314-3319, 1994. 

As shown in Figure 7 ethyl 3-hydroxyhexanoate, isolated from purple passion fruit possessed the (R)-configuration, comparable to the hydroxyacid ester obtained by the reduction with baker s yeast. In contrary to that methyl 3-hydroxyhexanoate, which was isolated from aroma extracts of pineapple, consisted of the (S)-enantiomer (91 %). ... 

The following experiment was conducted with a soluble starch in order to obtain solutions clear enough to permit determination of the optical activity. Reduction was determined with hypoiodite and calculated as degree of hydrolysis. Maltose and D-glucose were determined by fermentation with bakers yeast, Table II. The enzyme was quite... 

Scheme 9 Enzyme-mediated chemical transformations. (A) Enatioselective enzymatic oxidation and lactonization (B) enzyme reduction with baker s yeast and enantioselective rule and (C) enzymatic hydrolytic desymmetrization.

The synthesis starts with the enantioselective reduction of methyl 3-oxohex-5-enoate with bakers yeast. The enantiomeric excess amounts to 78 %, at a yield of around 60-70 %. Subsequently, the hydroxy-group is protected and the aldehyde function is introduced by ozonolysis. [267,268]... 

Geranial on reduction with Baker s yeast gave (R)-citronellol. However, reduction of the Z isomer (neral) gave a 6 4 R S mixture probably due to isomerisation of the double bond in neral prior to the delivery of hydrogen. ... 

Hydroxy-esters.—Ethyl 5-3-hydroxybutanoate is obtained in 87% optical purity by the reduction of ethyl acetoacetate with Bakers yeast. " Two independent chiral synthesis of the leukotriene intermediates (46), R = CHO and R = CH2OH, have appeared. An effective large-scale conversion of arachidonic acid into 5-hydroxy-6-fran5-8,ll,14-cis-eicosatetraenoicacid (5)HETE, including its resolution, is also reported by Corey and Hashimoto. ... 

Ethyl (5 )-3-hydroxybutanoate (3), obtained from the reduction of ethyl acetoacetate with bakers yeast, is readily converted into the tosylate (4). Its reaction with a lithium dialkylcuprate occurs with inversion of configuration to provide the acid (5) in 88—84% optical purity for three examples (Scheme 3). ... 

Kawai, Y, Saitou, K., Hida, K., and Ohno, A. (1995) Asymmetric reduction of a, 3-unsaturated ketones with bakers yeast. Tetrahedron Asymmetry, 6, 2143-2144. 

Nakamura K, Kawai Y, Miyai T, Honda S, Nakajrma N, Ohno A. Stereochemical control in microbial reduction. 18. Mechanism of stereochemical control in the diasteieoselective reduction with baker s yeast. Bull. Chem. Soc. Jpn. 1991 64 1467-1470. 

S) and (i )-P-Hydroxyvaleric acid ethyl ester were obtained from P-ketovaleric acid ethyl ester by reduction with baker s yeast and Thermoaerobium brockii, respectively (40% e.e. [12] and 84% e.e. [13], respectively). Mori et al. reported that high optical purity of (5)-P-hydroxyvaleric acid octyl ester (97.4% e.e.) was obtained when the long chain ester of P-ketovaleric acid was used for the baker s yeast reduction [14]. 

Even more highly selective ketone reductions are earned out with baker s yeast [61, 62] (equations 50 and 51) Chiral dihydronicotinamides give carbonyl reductions of high enantioselectivity [63] (equation 52), and a crown ether containing a chiral 1,4-dihydropyridine moiety is also effective [64] (equation 52). 

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