Pietro Cesti

Enzymatic resolution of 1,2-diols: preparation of optically pure dropropizine

Abstract Kinetic resolution of (R,S)-3-(4-phenyl-1-piperazinyl)-1,2-propanediol diacetate ( 2 ) by alcoholysis with n -propanol was carried out under lipase Amano PS catalysis in various organic solvents. Pure enantiomers of the corresponding diol ( 1 ) are useful as antitussive and central sedative therapeutic agents.

Characterization of Bio‐oil from Hydrothermal Liquefaction of Organic Waste by NMR Spectroscopy and FTICR Mass Spectrometry

Solid wastes of organic origins are potential feedstocks for the production of liquid biofuels, which could be suitable alternatives to fossil fuels for the transport and heating sectors, as well as for industrial use. By hydrothermal liquefaction, the wet biomass is partially transformed into a water-immiscible, oil-like organic matter called bio-oil. In this study, an integrated NMR spectroscopy/mass spectrometry approach has been developed for the characterization of the hydrothermal liquefaction of bio-oil at the molecular level. (1)H and (13)C NMR spectroscopy were used for the identification of functional groups and gauging the aromatic carbon content in the mixture. GC-MS analysis revealed that the volatile fraction was rich in fatty acids, as well as in amides and esters. High-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been applied in a systematic way to fully categorize the bio-oil in terms of different classes of components, according to their molecular formulas. Most importantly, for the first time, by using this technique, and for the liquefaction bio-oil characterization in particular, FT-MS data have been used to develop a methodology for the determination of the aromatic versus aliphatic carbon and nitrogen content. It is well known that, because they resist hydrogenation and represent sources of polluting species, both aromatic molecules and nitrogen-containing species raise concerns for subsequent upgrading of bio-oil into a diesel-like fuel.

Effects of chemical modification on stereoselectivity of Pseudomonas cepacia lipase

Abstract Two chemically modified forms of lipase from Pseudomonas cepacia were prepared by acylation of the free amino groups of the protein with acetic and succinic anhydrides. The catalytic activity, the enantioselectivity and the thermal stability of the modified enzymes were compared with that of the native form. Succinylation determined an increase of stability without affecting the catalytical properties of the enzyme in the hydrolysis of chiral esters. Acetylation resulted in an enhanced catalytic activity coupled to a decreased stereoselectivity and thermal stability.

STEREOSELECTIVE MICROBIAL HYDROLYSIS OF 2-ARYLOXYPROPIONITRILES

Abstract2-Aryloxypropionic acids 3a–f, compounds with herbicidal activity, have been prepared with high enantiomeric purity by microbial hydrolysis of the corresponding racemic nitriles and amides in presence ofBrevibacteriumimperiale cells.

RESOLUTION OF ISOPROPYLIDENE-GLYCEROL BENZOATE BY SEQUENTIAL ENZYMATIC HYDROLYSIS AND PREFERENTIAL CRYSTALLIZATION

Abstract Both enantiomers of isopropylidene-glycerol are prepared from its benzoate ester with enantiomeric excess ≥95% by combined partially stereoselective lipasecatalyzed hydrolysis and preferential crystallization.

Lipase-Catalyzed Resolution of Isopropylidene Glycerol: Effect of Co-Solvents on Enantioselectivity

The resolution of 1,2-O-isopropylidene glycerol via enzyme catalyzed hydrolysis of the corresponding benzoic ester was investigated. Using lipase PS from Pseudomonas cepacia, we determined the influence of organic co-solvents on the activity and enantioselectivity of the enzyme. The performance of the lipase was correlated to the nature (logP, ϵ,μ and the percentage of the organic media. The highest enzymatic activity was found in solvents completely miscible or completely immiscible in water. The enzyme stereoselectivity was inversely related to the logP of the solvent.

Enzymatic preparation of optically active fungicide intermediates in aqueous and in organic media

Pure stereoisomers of two new triazole and morpholine fungicides were prepared starting from enzymatically synthesized chiral alcohols intermediates. Two resolution strategies were compared: lipase-catalyzed hydrolysis of corresponding acetates in water and lipase-catalyzed transesterification of alcohols in organic solvent. The antifungal activity of optically pure enantiomers of the synthesized fungicides were investigated In vftro and in vfvo against a variety of fungi, showing an activity ratio (R-form / S-form) UP to 400.

Enzymatic resolution of 1,2-diols: comparison between hydrolysis and transesterification reactions

A new practical procedure for the enzymatic resolution of 1,2-diols 1a–e has been developed by lipase-catalysed regio- and enantio-selective esterification using anhydrides as acylating agents in organic solvents.

Process for the enzymatic separation of the optical isomers of racemic alpha -alkyl-substituted primary alcohols

A process is disclosed for the biotechnological resolution by means of enzymatic transesterification of the relevant racemic mixture of the optical isomers of alpha -alkyl-substituted alcohols having the formula (I): wherein: R represents a linear or branched (C1-C20)-alkyl or alkenyl group or an aryl group, also substituted or condensed with other groups, in particular a group of formula (II) or (III): wherein: R represents a (C1-C8)-alkyl group, a (C1-C4)-alkenyl group, an alkoxy, phenyl, phenoxy, benzoyl, heterocyclic group; R represents a hydrogen or halogen atom; R represents a (C1-C4)-alkyl group, and wherein R represents a (C1-C4)-alkyl group either equal to, or different from, R, in the presence of an enzyme either free or immobilized on a support capable of selectively causing the S isomer to be esterified, with the R isomer being left substantially unchanged, and said isomers are then separated according to techniques known from the prior art. The process is used in the synthesis of anti-inflammatory agents.

Enzymatic transformation of cephalosporin C to 7-ACA by simultaneous action of immobilized d-amino acid oxidase and glutaryl-7-ACA acylase

The enzymatic transformation of cephalosporin C (CEPH C) to 7-amino-cephalosporanic acid (7-ACA) using D-amino acid oxidase (DAO) and glutaryl-7-ACA acylase (G1-7-ACA) is reported. The enzymes have been immobilized separately on different carriers, in order to maximize the catalytic activity and the stability. The reaction has been carried out in single-step-like conditions, using the two enzymes simultaneously. The effect of catalase contamination, present in the DAO preparations, was balanced by addition of extra hydrogen peroxide. In optimum conditions, the conversion of CEPH C to 7-ACA was higher than 90%, with byproduct formation lower than 4%. The mixture of immobilized enzymes was reused in repeated reaction cycles, showing an appreciable operational stability.