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The optical resolution of some model monosubstituted cyclic carbonates, by inclusion in cholic acid, is described. The X-ray analysis of the host–guest crystal structures provide a rationale for molecular recognition.

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.

A guest dependent inversion of enantiomeric recognition operated by the host dehydrocholic acid on a second guest is observed during host–guest dehydrocholic acid–sulfoxide assembly formation.

Preparation of various heteroaryl propanols 2a‐g and of the corresponding propanones 3a‐g as starting materials for microbial redox is described. The kinetic resolution of the racemic propanols 2a‐g is obtained via oxidation with Pseudomonas paucimobilisand Bacillus stearothermophilus[(R)-alcohols, ee 74‐100%]. Similar results are achieved with 3-(2-hydroxypropyl)trifluoromethylbenzene 7 (44%, ee 100% of the (R)-alcohol 6). The reduction of the propanones 3a‐d and 3g with baker’s yeast and other fungi gives the ( S)-alcohols (ee 100%). The pure (S)-alcohols are also obtained by reduction of 1-[3-(trifluoromethyl)phenyl]-2-propanone 7. 1-[(4,4-Dimethyl)2-( 2 )oxazolinyl]-2-propanone 3e and 1[2-( 2 )-thiazolinyl)-2-propanone 3f are not reduced. The heterocyclic rings of (S)-5-(2-hydroxypropyl)-3-methylisoxazole 2d and of (S)-2-(2-hydroxypropyl)-4-methylthiazole 2g are deblocked to the homochiral enamino ketone 8 (78%) and to the protected -hydroxy aldehyde 9 (73%), respectively. The (R)-3-(2-hydroxypropyl)trifluoromethylbenzene 6 is transfomed into the homochiral precursor of (S)-fenfluramine 10 (overall yield 65%). © 1998 Elsevier Science Ltd. All rights reserved.

Various yeast and mould strains were tested in the microbial reduction of methyl-substituted bicyclo[3.2.0]hept-3-en-6-ones 1a-c . The endo -alcohols 2a-c were obtained with good yields and enantiomeric excess. Lower yields are described for the exo -alcohols 3a-c which are normally enantiomerically pure. Comparisons with microbial reduction of bicyclo[3.2.0]hept-2-en-6-one 1d and bicyclo[3.3.0]oct-7-en-2-one 1e are also reported.

Various yeast and mould suains were tested in the reduction of (α-acetyl-γ-butyrolactone. syn -(3R,1′R)-α(-(Hydroxyethyl)-γ-butyrolactone 2 and anti -(3R,1′S) isomer 3 were obtained enantiomerically pure. Good enantiomeric excesses are described for the corresponding enantiomers.

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.

Microbial reductions of β- and γ-nitroketones 1–3 with various yeast and mould species and strains is described. Enzyme mediated resolutions of the racemic β- and γ-nitro alcohols 4–6 and of their O-acetyl derivatives 4a–6a are also reported.

The synthesis of chiral 2-thiazolyl γ- and δ-lactones6 and7 via microbial reduction of the appropiate keto esters to the homochiral hydroxy esters followed by chemical lactonization is described. Some attempts of enzymatic lactonization of the racemic hydroxy esters or resolution of racemic lactones are also reported.

More than fifty yeast and mould strains were tested in the reduction of 2-acylthiazoles 1–5. The possibility of obtaining R or S enantiomers with high enantioselectivities from various species and strains is described.