Marco Fogagnolo

Anti-Prelog microbial reduction of prochiral carbonyl compounds

Abstract Yarrowia lipolytica strains isolated from various habitats were tested in the reduction of prochiral carbonyl groups. The anti-Prelog reduction ( R -enantiomer) is observed with different yields and enantiomeric excesses depending on the structure of the ketones 1a-e .

Thiazolylmethylenetriphenylphosporane and its benzo derivative: stable and practical wittig reagents for the synthesis of vinylthiazoles and vinylbenzo : two-carbon homologation of aldehydes

Abstract The title thiazolyl phosphorane is a stable yet quite reactive Wittig-type reagent which upon reaction with various aldehydes affords vinylthiazoles, mainly or exclusively as E -isomers, in very good yields. Also the benzothiazolyl phosphorane derivative, unlike a literature report, prove to react with aldehydes. Vinylthiazoles subjected to formyl deblocking from thiazole nucleous afford two-carbon homologated satured aldehydes. As an example, one of these vinylthiazoles, viz. the β-phenyl derivative 8f, proves to add n -butyl lithium cuprate to give after the formyl deblocking 3-phenylheptanal.

Combined microbial oxidation and reduction: a new approach to the highyield synthesis of homochiral unsaturated secondary alcohols from racemates

Abstract The oxidation of racemic secondary alcohols with Bacillus stearothermophilus followed by reduction of the mixture with Yarrowialipolytica to afford high yields of the enantiomerically pure R-alcohols 1a, b, d is described. Comparisons with Yarrowia lipolytica reduction, Bacillus stearothermophilus oxidation, and the contemporary use of the two microrganisms have been made.

Diastereoselectivity in the 1,2-addition of silylazoles to chiral aldehydes. Stereocontrolled homologation of α-hydroxyaldehydes.

Abstract The addition of 2-trimethylsilylazoles (thiazole, benzothiazole, oxazole) to α-asymmetric aldehydes give the corresponding O -silylcarbinols in good chemical yield and high stereoselectivity; the reaction is employed for the stereoselective homologation of D -glyceraldehyde.

Kinetic resolution of racemic secondary alcohols via oxidation with Yarrowia lipolytica strains

Abstract Cyclic and alicyclic racemic secondary alcohols are kinetically resolved via oxidation with Yarrowia lipolytica strains. The comparison of the oxidation reactions with the reductions of the corresponding ketones supports the hypothesis of the presence of two alcohol dehydrogenases with opposite enantioselectivity.

Stereospecific homologation of d-xylo and d-galacto dialdoses by 2-trimethylsilylthiazole

Abstract Homologation of the title dialdoses is carried out by diastereogenic addition of 2-trimethylsilylthiazole (1) to the side-chain aldehyde and unmasking the formyl group from thiazole ring; further addition of 1 to the resulting homologated dialdoses exhibited good levels of diastereoselectivity.

Asymmetric epoxidation of cinnamic acid derivatives using dioxiranes generated in situ from dehydrocholic acid

Abstract The asymmetric epoxidation of different cinnamic acid derivatives in water–NaHCO 3 has been achieved using dehydrocholic acid as the optically active ketone and Oxone® as the oxygen source (with product e.e. values of up to 75%).

Microbial oxidation with Bacillus stearothermophilus : high enantioselective resolution of 1-heteroaryl and 1-aryl alcohols

Abstract The enantioselective resolution of the racemic 1-heteroaryl- and 1-arylethanols 1a-h via microbial oxidation with Bacillus stearothermophilus to give the R -enantiomers with high enantiomeric excesses is described. The kinetic resolution of 1-(2-thienyl)ethanol 1b by oxidation with Acinetobacter calcoaceticus anitrat to S -enantiomer (ee 100%) is also reported.

Effect of high hydrostatic pressure and high pressure homogenization on the enantioselectivity of microbial reductions

Abstract The effect of high hydrostatic pressure and high pressure homogenization on the microbial reductions of the model prochiral ketones 1a-c is described. Various strains of Saccharomyces cerevisiae and Yarrowia lipolytica are utilized in the reduction and higher enantioselectivities are generally achieved together with lower yields compared with the results obtained at atmospheric pressure. In some cases both increasing yields and inversion of enantioselectivity are reported. The effects of the hydrostatic and the homogenization pressure are also compared with the cell viability.

Epoxidation of electrophilic alkenes in ionic liquids

A fast and efficient procedure is proposed for the epoxidation of electrophilic alkenes, the structures of which resemble the vitamin K class, in ionic liquids as solvents and using aqueous basic solutions of hydrogen peroxide as oxidant. Yields of epoxides ranging from very good to almost quantitative are observed for all the substrates analysed.