Hydride transfer versus electron transfer in the reduction of 4-phenyl-3-halo-3-buten-2-ones mediated by Pichia stipitis

Sequential chemo–biocatalytic synthesis of aroma compounds

“…48–50 Baker's yeast can catalyse the stereoselective reduction of carbonyl groups to produce alcohols, and therefore, is considered as a particularly key biocatalyst for the production of chiral alcohols starting from prochiral ketones and other dicarbonyl compounds. Additional relevant substrates for Baker's yeast are α,β-unsaturated ketones, such as α-haloenones, which allow access to chiral haloketones and halohydrins as building blocks for chemical synthesis, 51 and (4 R )-carvone, which yields dihydrocarvone and carveol, 52 and a variety of other compounds. 53 Poor chemoselectivity has been reported for the whole-cell bioreduction of enones and enals due to the competing CC and CO reduction catalysed by native enone reductases and dehydrogenases.…”

Enhancements of enantio and diastereoselectivities in reduction of (Z)-3-halo-4-phenyl-3-buten-2-one mediated by microorganisms in ionic liquid/water biphasic system

“…The substrates (Z)-3-bromo-4-phenyl-3-buten-2-one 1a and (Z)-3-chloro-4-phenyl-3-buten-2-one 1b were prepared following published methodologies [12]. The [bmim(PF 6 )] was prepared following a literature procedure [13] using 1-butyl-3-methylimidazolium trifluoromethanesulfonate and potassium hexafluorophosphate as starting materials.…”

“…The reduction products 3a-b were analyzed by 1 H NMR, 13 C NMR, IR spectra and are identical to those previously published [12]. 1 H NMR spectra were determined at 250 MHz (Varian Gemini 250) or 500 MHz (INOVA 500).…”

“…or 3b [12]. Our interest is to study the effect of the biphasic system water/[(bmim)PF 6 ] in these consecutive reactions mediated by microorganisms.…”