Copper-assisted substitution reaction for phenylthio group of a 4-phenylthioazetidinone derivative

Enantiocomplementary Bioreduction of 1-(Arylsulfanyl)propan-2-ones

This study explored the enantiocomplementary bioreduction of substituted 1-(arylsulfanyl)propan-2-ones in batch mode using four wild-type yeast strains and two different recombinant alcohol dehydrogenases from Lactobacillus kefir and Rhodococcus aetherivorans. The selected yeast strains and recombinant alcohol dehydrogenases as whole-cell biocatalysts resulted in the corresponding 1-(arylsulfanyl)propan-2-ols with moderate to excellent conversions (60-99%) and high selectivities (ee > 95%). The best bioreductions-in terms of conversion (>90%) and enantiomeric excess (>99% ee)-at preparative scale resulted in the expected chiral alcohols with similar conversion and selectivity to the screening reactions.

Rearrangement of 4-(1-haloalkyl)- and 4-(2-haloalkyl)-2-azetidinones into methyl omega-alkylaminopentenoates via transient aziridines and azetidines

The synthesis of 4-(1-haloalkyl)-2-azetidinones and 4-(2-haloalkyl)-2-azetidinones was investigated with use of the Staudinger reaction between in situ generated ketenes and alpha-haloimines or beta-haloimines. This new class of functionalized 2-azetidinones was further evaluated for its potential use as intermediates in the synthesis of highly functionalized compounds. The reaction of 4-(1-haloalkyl)-2-azetidinones and 4-(2-haloalkyl)-2-azetidinones with sodium methoxide in methanol yielded ring-opened products, i.e., methyl 2-alkoxy-4-(alkylamino)pentenoate and methyl 5-(alkylamino)pentenoate, respectively. Further attention was paid in detail to the reaction mechanism involved in this peculiar transformation. It was proven that these reactions proceeded via intermediate aziridines or azetidines.

Lipase mediated chiral resolution of 4-arylthio-2-butanol as an intermediate for β-lactam antibiotics

This paper deals with chiral enzymatic resolution of 4-arylthio-2-butanols by lipase to prepare potential intermediates of beta-lactam antibiotics. Among several lipases employed, lipase P type enzyme gave the highest ee value to prepare (R)-4-arylthio-2-butyl acetate. The enzymatic resolution of phenyl substituted alcohol (6a) using lipase P showed the highest ee value (99.7%) among those of 4-arylthio-2-butanol derivatives. Lipase P mediated hydrolysis of acylester 7a gave also (R)-alcohol 6a selectively. For determination of enantiomeric purity of these enzymatic resolved analytes, liquid chromatographic analysis was performed using two coupled Chiralcel OD and (R,R)-WhelkO chiral column.

[New orally active penem antibiotic: Farom]

An orally active penem antibiotic, Farom (generic name: faropenem), was designed by the conformational analysis of active and inactive penem derivatives. Faropenem showed potent activity against a wide variety of bacteria including extended-spectrum beta-lactamase (ESBL)-producing ones. The mechanism of the stability against ESBL was elucidated by modeling the Michaelis complex of faropenem and Toho-1, an ESBL. Modeling of a complex of faropenem at the active site of a penicillin-binding protein 2 (PBP2) model suggested the characteristic affinity for faropenem with PBP2 of Escherichia coli. Faropenem has been totally synthesized from (R)-1,3-butanediol. The synthetic intermediate, a 3-hydroxyethyl-4-acetoxyazetidinone derivative, was efficiently prepared by the 2 + 2 coupling of a optically active vinylsulfide derivative and chlorosulfonyl isocyanate, followed by the substitution of the acetoxy group for the thiophenyl group at the C-4 position.