Immobilized baker s yeast

Ionic liquid [bmimJPFg can be used as a solvent in yeast reduction [21]. The reduction ofketones with immobilized baker s yeast (alginate) in a 100 10 2 [bmimjPFfi ionic liquid water MeOH mix affords chiral alcohols (Figure 8.28). 

K Nakamura, M Higaki, K Ushio, S Oka, A Ohno. Stereochemical control of microbial reduction. 2. Reduction of (3-keto esters by immobilized baker s yeast. Tetrahedron Lett 4213-4216, 1985. 

Y Naoshima, J Maeda, Y Munakata, T Nishiyama, M Kamezawa, H Tachibana. Bioreduction with immobilized baker s yeast in hexane using alcohols as an energy source. J Chem Soc Chem Commun 964-965, 1990. 

Howarth J, James P, Dai J (2001) Immobilized baker s yeast reduction of ketones in an ionic liquid, [bmim]PF and water mix. Tetrahedron Lett 42 7517-7519... 

A detailed recipe has been given for the reduction of ethyl acetoacetate to ethyl-(S)-3-hydroxybutanoate (118) by Baker s yeast.Various forms of immobilized Baker s yeast can also be used,117 resulting in improved optical yields in some cases. 

Schemel2.12 Immobilized baker s yeast reduction of hydroxy keto ester 25.

Only a few studies in the literature reported malate production from fumarate using immobilized baker s yeast, Saccharomyces cerevisiae. Nevertheless, only one-third of the specific activity of yeast conversion is achieved as compared with the bacterial system (Oliveira et al., 1994). Neufeld et al. (1991) studied L-malate formation by immobilized S. cerevisiae that was amplified for fumarase in the presence of a surfactant. The highest specific activity... 

Yajima A, Naka K, Yabuta G. Immobilized baker s yeast reduction in fluorous media. Tetrahedron Lett. 2004 45 4577-4579. 

Calcium alginate [345-347] as well as K-carrageenan [348-350] has been used for immobilizing baker s yeast, and a sodium alginate/calcium chloride-immobilized baker s yeast has been used during the synthesis of d- and L-armentomycin [351]. This system has also been used for tiie reduction of several p-keto esters [352], and the antiselectivity as well as the yields was improved compared to reductions using classical conditions [217,353-355]. Calcium alginate-immobilized cells of S. cerevisiae were pretreated at 50 °C for 30 min, and tiien the cells showed an increased performance (80%) and an excellent selectivity (ee 99%) in the reduction of 3-chloropropiophenone... 

The reduction of acefylfrimethylsilane [387, 388] by immobilized baker s yeast using two different ionic liquid buffer sysfems was studied in more detail, and the effects of temperature and pH were investigated. Finally high )delds (>99%) and superior enantioselectivity (ee>99.9%) could be obtained [382]. 

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