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Nitromethylation of nitrones occurred efficiently in CH3NO2 in the presence of tetramethylammonium fluoride or triazabicyclodecene as promoters. The obtained adducts might be conveniently transformed into vicinal diamines. The process was extended to nitroethane and nitropropane affording mixtures of syn and anti stereoisomers with low diastereoselectivity. Comprehensive study of the addition of nitroalkanes to nitrones was conducted. The reaction proved efficient with TMAF or TBD as bases, in the presence of a large excess of R–NO2. Phase‐transfer catalysis gave also acceptable yields. Nitroethane or nitropropane afforded mixtures of isomerisable diastereomers. The reaction was applied to the synthesis of biologically relevant compounds. [ABSTRACT FROM AUTHOR]

Synthetic analogues of the naturally occurring iminosugar homoDMDP, which feature a perfluoroalkyl group at the pseudo-anomeric position, have been synthesized from the corresponding sugar-derived cyclic aldonitrone. The new fluorinated iminosugars as well as homoDMDP and its 6-deoxy counterpart were evaluated for their inhibitory activity against a panel of glycosidases. While the replacement of the (1′,2′)-dihydroxyethyl substituent of homoDMDP with –C 4 F 9 proved detrimental for enzyme binding, introduction of a –C 3 F 7 moiety tuned the inhibitory activity spectrum selectively towards α-fucosidase and α-glucosidase from yeast. [ABSTRACT FROM AUTHOR]

Heavy metal on Lewis acid: The combination of lanthanide metals and AlCl3 has been employed for selective single C−F activation in benzofulvenes comprising an exocyclic CF3 substituent. Intermediate ϵ,ϵ-difluorinated metal-dienyl species react with a large variety of aldehydes in a highly regio- and diastereoselective fashion to afford 1,1-disubstituted indenes bearing a difluorovinyl group. These new building blocks have been further transformed through a hydrogenation-cyclization process into fluorinated heterocyclic spiro compounds. [ABSTRACT FROM AUTHOR]

An efficient (+)-camphor-mediated kinetic resolution of racemic cyclohex-2-en-1-ylalane is described. This approach provides an enantiomerically enriched form of the alane, in situ available for synthetic uses. Applied to the allylation of aldehydes, this protocol leads to the corresponding homoallylalcohols in a highly enantioselective manner. [ABSTRACT FROM AUTHOR]

Cycloadditions of nitrones with alkynes usually occur best under heat activation. Due to the instability of the formed isoxazolines, alternative activation methods must be found. Here, hyperbaric conditions are used to transform nitrones generated from unprotected carbohydrates into the corresponding polyhydroxy-isoxazolines at room temperature. The reaction proved completely regioselective in favor of the 5-substituted 4-isoxazolines, and the products are obtained in good yields as mixtures of the two possible diastereoisomers. Further transformations into biologically valuable targets are described. The whole synthesis constitutes a very straightforward procedure for the transformation of aldoses, and is highly compatible with the principles of green chemistry. [ABSTRACT FROM AUTHOR]

The diastereoselective nucleophilic trifluoromethylation of a range of ketoamides derived from L-tartaric acid has been studied. TMSCF3 in the presence of a catalytic amount of K2CO3 in DMF has been identified as the conditions leading to the highest diastereoselectivities. A sequential one-pot reaction trifluoromethylation-etherification of the trifluoromethylcarbinol has been developed. Only one further one-pot reaction, ketal hydrolysis-oxidative cleavage, led to the final α-trifluoromethylated α-alkoxy-aldehydes. This procedure was applied to the preparation of a series of enantiopure aryl, heteroaryl, and alkyl α-trifluoromethyl-α-alkoxyaldehydes [ABSTRACT FROM AUTHOR]

A highly diastereoselective nucleophilic mono(trifluoromethylation) of a tartaric acid-based diketone, using trifluoromethyl(trimethyl)silane, afforded the corresponding γ-keto trifluoromethylcarbinol. The scope and limitation of this reaction was studied. The acidic removal of the acetonide moiety protecting the two hydroxyl groups of the adducts was unsuccessful. Bis(O-methylation) of the aromatic derivatives under basic conditions, followed by acidic hydrolysis and oxidative cleavage, led to two different enantiopure products: an α-aryl-α-methoxy-α-trifluoromethyl ethanal and an α-aryl-α-methoxycarboxylic acid. The overall process is eventually an interesting way to convert one natural chiral raw material into two functionalized enantiopure building blocks including a trifluoromethyl one. [ABSTRACT FROM AUTHOR]

The preparation of aliphatic, aromatic or functionalized tartramides directly from tartaric acid and amines under microwaves activation is described. A preliminary study of the chelating properties of some functionalized tartramides towards Cu2+ ions is reported. To cite this article: R. Plantier-Royon, C. R. Chimie 7 (2004). [Copyright &y& Elsevier]

IspG (also called GcpE) is an oxygen‐sensitive [4Fe‐4S] enzyme catalyzing the penultimate step of the methylerythritol phosphate (MEP) pathway, a validated target for drug development. It converts 2‐C‐methyl‐d‐erythritol‐2,4‐cyclo‐diphosphate (MEcPP) into (E)‐4‐hydroxy‐3‐methyl‐but‐2‐enyl‐1‐diphosphate (HMBPP). The reaction, assimilated to a reductive dehydration, involves redox partners responsible for the formal transfer of two electrons to substrate MEcPP. The 2‐vinyl analogue of MEcPP was designed to generate conjugated species during enzyme catalysis, with the aim of providing new reactive centers to be covalently trapped by neighboring amino acid residues. The synthesized substrate analogue displayed irreversible inhibition towards IspG. Furthermore, we have shown that electron transfer occurs prior to inhibition; this might designate conjugated intermediates as probable affinity tags through covalent interaction at the catalytic site. This is the first report of an irreversible inhibitor of the IspG metalloenzyme. [ABSTRACT FROM AUTHOR]

The development of new fluorine‐containing building blocks and their efficient synthetic access is currently a challenging research field. Herein, the highly regio‐ and stereoselective addition of a large range of aldehydes onto trifluoromethylated benzofulvenes was achieved using a simple La/I2/DIBAL‐Cl system via a selective C−F bond activation process. This versatile methodology provided homodienyl alcohols bearing a terminal CF2‐alkene with potential further applications, as shown by the dehydration to the first benzofulvenes carrying a difluorovinyl group. In addition, for certain electron‐poor aldehydes, unprecedented ipso substitution of the CF3 group in a diene was observed, which, according to DFT studies, is related to the presence of the large, Lewis‐acidic lanthanum metal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Protecting-group-free synthesis of glycoconjugates. • Cycloadditions under Microwave activation. • Strong antifungal isoxazolidines obtained in good yields and few steps. • Potential use as crop-protecting agents. A straightforward synthesis of carbohydrate templated isoxazolidines is described, by reaction of unprotected glycosylhydroxylamines (operating as 1,3-dipoles) with methyl acrylate using microwave activation. Rhamno - and erythro -isoxazolidines are recognized by plant cells, resulting in a strong ROS-production as a plant immune response, and exert a high antifungal activity against Botrytis cinerea. [ABSTRACT FROM AUTHOR]

The reaction of low-valent zirconocene reagents formed either from the Negishi reagent Cp2Zr(n-butyl) 2 or from the reduction of Cp2ZrCl2 with Mg with various pentafulvenes yielded the first zirconocene-pentafulvene complexes, Cp2ZrFv (Fv = 6,6-di(aryl), 6,6'-adamantylidene, and 6-tert-butylfulvene), which are formal 20-electron complexes. In addition to NMR spectroscopic analysis and DFT calculations, three complexes were characterized by X-ray crystallography, showing a η5:η¹ dianionic binding mode of the fulvene to the metal. The obtained complexes react with carbonyl compounds (aldehydes and ketones) to unexpectedly afford double-insertion products, as shown by NMR spectroscopy and X-ray studies. In the case of aldehydes these diolate complexes were obtained as single diastereoisomers. The reaction of Cp2ZrFv with internal alkynes did not result in the formation of insertion products but release of the coordinated fulvene and reductive dimerization of the alkynes to the corresponding zirconacyclopentadienes. [ABSTRACT FROM AUTHOR]

[4Fe-4S] enzymes, fraudulent substrates, irreversible inhibition, IspG (GcpE), MEP pathway Cover Feature: Irreversible Inhibition of IspG, a Target for the Development of New Antimicrobials, by a 2-Vinyl Analogue of its MEcPP Substrate (Chem. Eur. J. 30/2022) Keywords: [4Fe-4S] enzymes; fraudulent substrates; irreversible inhibition; IspG (GcpE); MEP pathway EN [4Fe-4S] enzymes fraudulent substrates irreversible inhibition IspG (GcpE) MEP pathway 1 1 1 05/27/22 20220525 NES 220525 B The rational design b of a substrate analogue has afforded the first irreversible inhibitor of an IspG enzyme, a target for the development of new drugs to fight antimicrobial resistance. [Extracted from the article]

Abstract: The interactions of three bis(amide) ligands derived from tartaric acid with copper (II) were investigated in aqueous solution by a combination of potentiometry, UV–vis spectrophotometry, electron paramagnetic resonance (EPR), and mass spectrometry. The formation constants of the complexes were measured and their relative structures were reported. The sites of complexation of these ligands are investigated based mostly on their electronic and EPR spectra and on the comparison with the behaviour of some analog compounds. [Copyright &y& Elsevier]