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Whole seeds of Bauhinia variegata L. (Fabaceae) were utilized as a biological reducer to transform benzaldehyde into benzyl alcohol. The effects of some variables such as temperature, the load of substrate and co-solvent, were established to optimize the reductive process. Utilizing the optimal reaction conditions, a laboratory-scale reaction (final concentration of the substrate: 21.2 mM) was performed to obtain benzyl alcohol (conversion: 95%; isolated yield: 49%; productivity: 1.11 g L−1 or 0.046 g L−1h−1 of benzyl alcohol). In addition, using these optimal conditions, fourteen substituted benzaldehydes were reduced, with a conversion achieved to their corresponding benzyl alcohols ranging from 62% to >99% (isolated yields from 7% to 70%). Moreover, useful building blocks by the synthesis of the drugs and important commercial products were also obtained. The scope, limitations and advantages of this new biocatalytic synthetic method are also discussed. [ABSTRACT FROM AUTHOR]

The acetophenone stereoselective reduction reactions carried out by different chemical or biochemical methodologies reported in the literature were analyzed. This study showed the importance of evaluation in each reaction step, both holistically and quantitatively, even if the amounts used are at the mmol level. It is clear that the use of catalysts does not guarantee that the chemical process is environmentally friendly, as well as that the benefits of bio-driven processes can be diminished due to the complications of product purification. This work shows that the development of tools to determine the sustainability of a process is extremely important. [ABSTRACT FROM AUTHOR]

2, 4-dinitrophenyl is the sole product of the reactions of 3-butenyl 2, 4-dinitrophenyl ether, allyl 2,4-dinitrophenyl ether and n-butyl 2, 4-dinitrophenyl ether with KOH in two DMSO-water mixtures. An analysis of these reactions provides no proof of a single electron transfer process. The conventional SNAr process is evident in this reaction.

With the aim of finding new methods for environmentally friendly synthesis of chiral phenylethanols, a screening was carried out to identify seeds that could be used as a biocatalyst capable of reducing stereoselectively prochiral ketones. As a result, seeds of Bauhinia variegata L. (Fabaceae) were identified as being an efficient and stereoselective biological reducer of acetophenone to produce (S)-1-phenylethanol (conversion of 98% and 99 e.e.%). Then, to optimise the reductive process, the effects of some variables such as temperature, load of substrate, pH, co-solvent, and reuse and storability of the seeds as a function of time were established. Utilising the optimal reaction conditions, nineteen substituted acetophenones were reduced to their corresponding chiral alcohols with a conversion ranging from 30% to 98% and enantiomeric excess of between 65% and >99%, and in addition, useful key intermediates were also obtained by the synthesis of drugs. The scope and advantages of this new biocatalytic synthetic method are also discussed. A screening was carried out to identify seeds that could be used as a biocatalyst Seeds of Bauhinia variegata have been identified as an efficient biocatalyst to reduce carbonyl compounds. Acetophenone and substituted acetophenones were reduced with high stereoselectivity. Some key intermediates were synthetised using this methodology. Seeds can be stored for twenty-four months without loss of activity. [ABSTRACT FROM AUTHOR]

The fruits of Ligustrum lucidum were used as an efficient biological reducer of carbonyl compounds, and trials were carried out to optimise the reductive process using acetophenone as the model substrate. In order to try to eliminate the dependence on the seasonal production of the fruits, a study was carried out to find ways to conserve them. The results reported here show that it is possible to store the dehydrated fruits of glossy privet at room temperature over a prolonged period of time, during which time they can be used as a common chemical reagent. On the other hand, studies performed on different parts of the fruits established that the seeds are responsible for the bioreduction process, with the best reduction conditions found being isolated seeds from the fruits of glossy privet at 25 °C, in a 100 mM phosphate buffer pH 6.0, using 0.67% w/v of DMSO as co-solvent with an acetophenone charge of 2.67 g/L (22 mM). Moreover, seed reuse studies showed that it is possible to recycle them, providing almost the same activity and enantioselectivity from the first to the fifth cycle, without any loss of biocatalytic properties. Finally, using whole seeds of glossy privet in optimal reaction conditions, important alcohols useful as key intermediates in the synthesis of industrial products were obtained on a laboratory scale through the reduction of specially selected ketones and aldehydes. [ABSTRACT FROM AUTHOR]

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A mixture of cis and trans 2-decene is produced on the isomerization of 1-decene to 2-decene in homogenous solution with ((Ph)3P)2Co(SCN)2/BH4Na as catalyst. Thermodynamically unstable products are obtained if the reaction is terminated when 90% of the conversion has taken place and the cis to trans ratio is one. The reactions are reproducible in the absence of oxygen and humidity.

Copyright of Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas is the property of Universidad de Santiago de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract A mechanistic interpretation of the kinetic profiles obtained for the stereoselective reduction of acetophenone promoted by Galactomyces candidus GZ1 under aerobic and anaerobic conditions was made. Based on experimental and bibliographical data, a mechanism which may involve the participation of two alcohol dehydrogenases with opposite stereoselectivities and alcohol oxidase is discussed. Due to the stereoselectivity of the reduction of acetophenone being changed when anaerobic conditions were used, this microorganism also permitted (S)-1-phenylethanol to be obtained in the absence of oxygen. Moreover, the kinetic profiles of the reactions of a racemic mixture of (R , S)-1-phenylethanol and pure (S)-1-phenylethanol with Gal. candidus were analyzed, which corroborated that there existed a reaction step where (S)-1-phenylethanol was oxidized to acetophenone. The results presented here show that not only is it possible to resolve racemic mixtures of phenylethanols when Gal. candidus is used as a biocatalyst, but that this is also efficient in causing the complete stereoinversion of pure (S)-1-phenylethanol to (R)-1-phenylethanol. Graphical abstract fx1 Highlights • Mechanism of the reduction of acetophenone catalyzed by Gal. candidus was studied. • Kinetic profile in aerobic and anaerobic conditions were obtained. • Anaerobic conditions invert the stereoselectivity of the reaction. • Participation of two alcohol dehydrogenase and an alcohol oxidase is discussed. • Due to the results obtained, other potential use of Gal. candidus were identified. [ABSTRACT FROM AUTHOR]

Twenty strains of fungi isolated from food samples were screened for the asymmetric reduction of acetophenone. A dimorphic fungus denominated initially as GZ1 and isolated from a carrot sour rot showed very high reduction activities, and based on phenotypic and genetic characteristics was identified as Galactomyces candidus. The only product of the reduction was confirmed to be ( R )-1-phenylethanol. The bioreduction conditions mediated by Gal. candidus GZ1 were investigated, and the optimal conditions in terms of acetophenone concentration, temperature, pH media, co-solvent, the charge of inoculum and shaking speed were established. Under the optimal conditions of 1.875 g/L of acetophenone dissolved in DMSO (1.25% v/v), 112.5 g/L of microorganism cells in 100 mM sterile phosphate buffer solution at pH 7.0, 25 °C and 150 rpm, the conversion and enantiomeric excess values after 48 h reaction were 99% and > 99.9%, respectively. A preparative scale reaction of ( R )-1-phenylethanol was made and the isolated yield was 82% with > 99.9 e.e.%. Additionally, a study using several substituted acetophenones was carried out, and the advantages and scope of GZ1 in the production of chiral 1-phenylethanols were established. In this sense, good results were obtained with 3′-hydroxyacetophenone and a preparative scale reaction was performed which give ( R )-1-(3′-hydroxyphenyl)ethanol (key intermediate of Rivastigmine) with 53% of isolated yield and > 99.9 e.e.%. [ABSTRACT FROM AUTHOR]

This paper describes the search for novel vegetal biocatalysts for the stereoselective reduction of prochiral phenylketones. In this study, twenty native weeds were tested and Eryngium horridum Malme (Apiaceae) was proven to be an effective biocatalyst for the stereoselective reduction of acetophenone to ( S )-1-phenylethanol (96% conversion, >99.9 e.e.%). Using this biocatalyst, fourteen chiral ( S )-phenylethanols with excellent enantiomeric excesses (>98%) and variable conversions (30–100%) were obtained. [ABSTRACT FROM AUTHOR]

The screening of four invasive plant species for use as biocatalysts in the stereoselective reduction of ketones is reported. Our studies revealed that fruits of Ligustrum lucidum can be used for the bioreduction of acetophenone to ( S)-1-phenylethanol (94% conversion, > 99 enantiomeric excess [ee]%). Using this methodology, 13 substituted ( S)-phenylethanols were synthesized with good ee values (> 99.9 to 78%) using a technique which is more environmentally friendly than classical reduction of prochiral ketones. The results reveal the fruits of L. lucidum to be promising biocatalysts for the production of key intermediates. [ABSTRACT FROM AUTHOR]

Copyright of Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas is the property of Universidad de Santiago de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As part of our project devoted to the search of new antifungal agents, we report here the in vitro–in vivo antifungal evaluations and a structure–activity relationship (SAR) study of 17 thione derivatives.Some compounds of this series exhibited remarkable antifungal activity against a broad spectrum of pathogenic opportunistic fungi. SAR studies provide a useful information for the determination of the minimum structural requirements for producing the biological response. [Copyright &y& Elsevier]