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Reduction keto esters

A representative set of a- and -keto esters was also tested as substrates (total 11) for each purified fusion protein (Figure 8.13b,c) [9bj. The stereoselectivities of -keto ester reductions depended both on the identity of the enzyme and the substrate stmcture, and some reductases yielded both l- and o-alcohols with high stereoselectivities. While a-keto esters were generally reduced with lower enantioselec-tivities, it was possible to identify pairs of yeast reductases that delivered both alcohol antipodes in optically pure form. These results demonstrate the power of genomic fusion protein libraries to identify appropriate biocatalysts rapidly and expedite process development. [Pg.201]

Rodriguez, S., Kayser, M.M. and Stewart, J.D. (2001) Highly stereoselective reagents for/3-keto ester reductions by genetic engineering of baker s yeast. Journal of the American Chemical Society, 123 (8), 1547-1555. [Pg.162]

In keto esters reduction can affect the keto group and convert it to an alcoholic group or to a methylene group, or else it can hydrogenolyze the ester group, either to an acid or to an alcohol. The latter reduction may be accompanied by the reduction of the keto group at the same time. [Pg.161]

K Nakamura, K Inoue, K Ushio, S Oka, A Ohno. Stereochemical control on yeast reduction of a-keto esters. Reduction by immobilized bakers yeast in hexane. J Org Chem 53 2589-2593, 1988. [Pg.204]

S Rodriguez Giordano. Baker s yeast (3-keto ester reductions whole cell biocatalysts with improved stereoselectivity by recombinant DNA techniques. Ph.D. thesis, University of Florida, Gainesville, FL, 2000. [Pg.206]

Alcohol derivatives 1.155 (Y = CHOHR) are useful as auxiliaries in a-keto-ester reductions [540] or [4+2] cycloadditions of aciylates [548]. 6-Lactams are obtained from imines 1.155 (Y = CH=NAr) with a high enantiomeric excess after reaction with ester enolates and decomplexation [549]. Alkylations of benzylimine 1.155 (Y = Ph2N=CH) give interesting results [539], and some 1,3-dipdar cycloaddition reactions with nitrones have been described [550],... [Pg.85]

It has been shown that the forces which induce asymmetry in a-keto ester reductions cannot operate through a phenyl nucleus (Kubitscheck and Bonner 1961 Bonner 1963). Lithium aluminum hydride reduction of (—)-menthyl p-benzoylbenzoate (III), a Aiinylog of the a-keto acid used by McKenzie (Fig. 1), yielded... [Pg.153]

As was the case with a-keto acids and esters, there are two situations which give rise to the asymmetric reduction of a ketone. Hydrogen transfer from an optically active reducing agent to the carbonyl carbon of an inactive ketone is one possibility. Asymmetric reduction may also be produced by hydrogen transfer to a keto carbonyl adjacent to an asymmetric center. The latter type of reaction has been studied extensively by Cram and his coworkers. Inspection of the necessary conditions for this kind of asymmetric reduction reveals some similarity to the keto ester reductions described in Section II. [Pg.158]

The reduction of different y-chloroacetoacetates 58 and 59 (Figure 21.18) has been studied quite often and in more detail, and its stereochemical course (to 5ueld products 60 and 61, respectively) can be altered by changing the size of the ester moiety [17, 248, 255, 256]. The addition of a nonpolar resin to the reaction mixture also increased yields and selectivity [257], Recently, enantioselective keto ester reductions in water have been accomplished either by baker s yeast or by ruthenium-catalyzed reactions interestingly enough, the highest ee values have been obtained using S. cerevisiae [258]. In addition, a metabolic in vivo study has been performed. These data revealed that under aerobic conditions the reduction occurs preferentially in the mitochondrial matrix, while under anaerobic conditions the bioreduction occurs in the cytosol [259]. [Pg.528]


See other pages where Reduction keto esters is mentioned: [Pg.218]    [Pg.365]    [Pg.243]    [Pg.253]    [Pg.215]    [Pg.187]    [Pg.331]    [Pg.107]    [Pg.75]   
See also in sourсe #XX -- [ Pg.161 , Pg.162 , Pg.198 ]

See also in sourсe #XX -- [ Pg.191 ]

See also in sourсe #XX -- [ Pg.191 ]




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3-Keto esters

3-keto esters, borohydride reduction

A-keto ester reduction

Aliphatic (3-keto ester reduction

Asymmetric reduction of P-keto esters

Asymmetric reduction of a-keto esters

Biochemical reductions keto esters

Cyclic P-keto esters reduction with yeast

Esters reduction

Keto ester reduction with yeast

Keto esters enzymic reductions

Keto reduction

Oximes keto esters, reduction

P-keto ester reduction

Reduction of Keto Esters

Reductive amination keto esters, enantioselective

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