Editorial Catalysts: Supported Metal Catalysts and Their Applications in Fine Chemicals

Editorial to the Special" Issue Supported Metal Catalysts and Their Applications in Fine Chemicals

New Polymer-Supported Mono- and Bis-Cinchona Alkaloid Derivatives: Synthesis and Use in Asymmetric Organocatalyzed Reactions

The straightforward synthesis of polystyrene-supported Chinchona alkaloids and their application in the asymmetric dimerization of ketenes is reported. Six different immobilized derivatives, consisting of three dimeric and two monomeric 9-O ethers, were prepared by “click” anchoring of soluble alkaloid precursors on to azidomethyl resins. The resulting insoluble polymer-bound (IPB) organocatalysts were employed for promoting the dimerization of in-situ generated ketenes. After opening of the ketene dimer intermediates with N,O-dimethylhydroxylamine, valuable Weinreb amides were eventually obtained in good yield (up to 81 %) and excellent enantiomeric purity (up to 96 % ee). All of the IPB catalysts could be recycled effectively without significant loss of activity and enantioselectivity. The extension to other asymmetric transformations (meso-anhydride desymmetrization and α-amination of 2-oxindoles) is also briefly discussed

A Catalytic Reactor for the Organocatalyzed Enantioselective Continuous Flow Alkylation of Aldehydes

The use of immobilized metal-free catalysts offers the unique possibility to develop sustainable processes in flow mode. The challenging intermolecular organocatalyzed enantioselective alkylation of aldehydes was performed for the first time under continuous flow conditions. By using a packed-bed reactor filled with readily available supported enantiopure imidazolidinone, different aldehydes were treated with three distinct cationic electrophiles. In the organocatalyzed α-alkylation of aldehydes with 1,3-benzodithiolylium tetrafluoroborate, excellent enantioselectivities, in some cases even better than those obtained in the flask process (up to 95 % ee at 25 °C), and high productivity (more than 3800 h−1) were obtained, which thus shows that a catalytic reactor may continuously produce enantiomerically enriched compounds. Treatment of the alkylated products with Raney-nickel furnished enantiomerically enriched α-methyl derivatives, key intermediates for active pharmaceutical ingredients and natural products

Comparison between fermentation and ultrasound‐assisted extraction: Which is the most efficient method to obtain antioxidant polyphenols from sambucus nigra and punicagranatum fruits?

Fruit extracts of Sambucus nigra L. (elderberry) and Punica granatum L. (pomegranate) have several applications in nutraceutical, cosmetics, and pharmaceutical industries thanks to their richness in antioxidant polyphenols, whose composition changes with the extraction method applied. We aimed to compare the efficiency of the fermentation extraction, recently applied by industries, with the ultrasound‐assisted extraction–UAE, a well‐known and efficient technique, on the yield of antioxidant polyphenols from elderberry fruits and pomegranate fruit‐peels. Extracts were obtained by both methods, analyzed by high‐performance liquid chromatography (HPLC) and the antioxi-dant capacities were evaluated using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and Hydroxyl Radical Scavenging (HRS) assays. The main compounds detected in elderberry were caffeoyl and quercetin derivatives, present in higher amounts in UAE extracts. In pomegranate, punicalagin were the main constituents, also detected in higher contents in the UAE extracts compared to fermented ones. The UAE was more suitable for extracting anthocyanins from pomegranate. In addition, higher antiox-idant capacities were observed in UAE extracts, possibly due to their richness in polyphenols. Therefore, despite the recent wide applicability and the good performance of the fermentation pro-cess, the UAE may be considered more efficient for the extraction of polyphenols from S. nigra and P. granatum fruits and may be used to obtain polyphenolic antioxidant extracts to be applied by several industries

Advances in mosquito repellents: effectiveness of citronellal derivatives in laboratory and field trials

BACKGROUND Several essential oils, including citronella (lemongrass, Cymbopogon sp., Poaceae), are well-known mosquito repellents. A drawback of such products is their limited protection time resulting from the high volatility of their active components. In particular, citronella oil protects for <2 h, although formulations with fixatives can increase this time. RESULTS We synthesized hydroxylated cyclic acetals of citronellal, the main component of citronella, to obtain derivatives with lower volatility and weaker odour. The crude mixture of isomers obtained in the reaction was tested under laboratory conditions for its repellency against two mosquito species, the major malaria vector Anopheles gambiae and the arbovirus vector Aedes albopictus, and found to be endowed with longer protection time with respect to DEET (N,N-diethyl-meta-toluamide) at the same concentration. Formulated products were tested in a latin square human field trial, in an area at a high density of A. albopictus for 8 h from the application. We found that the performance of the citronellal derivatives mixture is comparable (95% protection for <= 3.5 h) with those of the most widespread synthetic repellents DEET and Icaridin, tested at a four-fold higher doses. CONCLUSIONS Modifying the hydrophilicity and volatility of natural repellents is a valuable strategy to design insect repellents with a long-lasting effect. (c) 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

AML associated oncofusion proteins PML-RARA, AML1-ETO and CBFB-MYH11 target RUNX/ETS-factor binding sites to modulate H3ac levels and drive leukemogenesis

Chromosomal translocations are one of the hallmarks of acute myeloid leukemia (AML), often leading to gene fusions and expression of an oncofusion protein. Over recent years it has become clear that most of the AML associated oncofusion proteins molecularly adopt distinct mechanisms for inducing leukemogenesis. Still these unique molecular properties of the chimeric proteins converge and give rise to a common pathogenic molecular mechanism. In the present study we compared genome-wide DNA binding and transcriptome data associated with AML1-ETO, CBFB-MYH11 and PML-RARA oncofusion protein expression to identify unique and common features. Our analyses revealed targeting of oncofusion binding sites to RUNX1 and ETS-factor occupied genomic regions. In addition, it revealed a highly comparable global histone acetylation pattern, similar expression of common target genes and related enrichment of several biological pathways critical for maintenance of AML, suggesting oncofusion proteins deregulate common gene programs despite their distinct binding signatures and mechanisms of action.Peer reviewe

Unravelling main- and side-chain motions in polymers with NMR spectroscopy and relaxometry: The case of polyvinyl butyral

Polyvinyl butyral (PVB) is an amorphous polymer employed in many technological applications. In order to highlight the relationships between macroscopic properties and dynamics at a microscopic level, motions of the main-chain and of the propyl side-chains were investigated between Tg − 288◦ C and Tg + 55◦ C, with Tg indicating the glass transition temperature. To this aim, a combination of solid state Nuclear Magnetic Resonance (NMR) methods was applied to two purposely synthesized PVB isotopomers: one fully protonated and the other perdeuterated on the side-chains.1 H time domain NMR and1 H field cycling NMR relaxometry experiments, performed across and above Tg, revealed that the dynamics of the main-chain corresponds to the α-relaxation associated to the glass transition, which was previously characterized by dielectric spectroscopy. A faster secondary relaxation was observed for the first time and ascribed to side-chains. The geometry and rate of motions of the different groups in the side-chains were characterized below Tg by2 H NMR spectroscopy

Supported tris-triazole ligands for batch and continuous-flow copper-catalyzed huisgen 1,3-dipolar cycloaddition reactions

The lack of supported versions of the tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) ligand, suitable for flow-chemistry applications at scale, prompted us to develop a new route for the immobilization of such tris-triazole chelating units on highly cross-linked polystyrene resins. With this aim, the preparation of the known TBTA-type monomer 3 was optimized to develop a high-yield synthetic sequence, devoid of chromatographic purifications at any stage. Then, bead-type (P7) and monolithic (M7) functional resins were obtained by the easy and scalable suspension-or mold-copolymerization of 3 with divinylbenzene. Both types of materials were found to possess a highly porous morphology and specific surface area in the dry state and could be charged with substantial amounts of Cu(I) or Cu(II) salts. After treatment of the latter with a proper reducing agent, the corresponding supported Cu(I) complexes were tested in the copper-catalyzed alkyne-azide cycloaddition reaction (CuAAC). The immobilized catalysts proved active at room temperature and, in batch and with catalyst loadings as low as 0.6 mol%, afforded quantitative conversions within 20 h. Independent of the alkyne structure, extended use of the supported catalyst in flow was also possible. In the reaction of benzylazide and propargyl alcohol, this allowed a total turnover number larger than 400 to be reached

An insoluble polymer-bound phosphoramidite for the copper-catalysed enantioselective 1,4-addition of ZnEt2 to 2-cyclohexenone

The preparation of a chiral phosphoramidite ligand anchored to a Merrifield resin has been studied and its use in the copper-catalysed heterogeneous enantioselective conjugate addition of ZnEt2 to 2-cyclohexenone investigated. The insoluble polymer bound ligand could be recovered quantitatively by filtration, affording e.e. values in the range 65-84%, in the course of successive recycle runs. (C) 2003 Elsevier Ltd. All rights reserved

Complete Plastome Sequences of Equisetum arvense and Isoetes flaccida: Implications for Phylogeny and Plastid Genome Evolution of Early Land Plant Lineages

Background Despite considerable progress in our understanding of land plant phylogeny, several nodes in the green tree of life remain poorly resolved. Furthermore, the bulk of currently available data come from only a subset of major land plant clades. Here we examine early land plant evolution using complete plastome sequences including two previously unexamined and phylogenetically critical lineages. To better understand the evolution of land plants and their plastomes, we examined aligned nucleotide sequences, indels, gene and nucleotide composition, inversions, and gene order at the boundaries of the inverted repeats. Results We present the plastome sequences of Equisetum arvense, a horsetail, and of Isoetes flaccida, a heterosporous lycophyte. Phylogenetic analysis of aligned nucleotides from 49 plastome genes from 43 taxa supported monophyly for the following clades: embryophytes (land plants), lycophytes, monilophytes (leptosporangiate ferns + Angiopteris evecta + Psilotum nudum + Equisetum arvense), and seed plants. Resolution among the four monilophyte lineages remained moderate, although nucleotide analyses suggested that P. nudum and E. arvense form a clade sister to A. evecta + leptosporangiate ferns. Results from phylogenetic analyses of nucleotides were consistent with the distribution of plastome gene rearrangements and with analysis of sequence gaps resulting from insertions and deletions (indels). We found one new indel and an inversion of a block of genes that unites the monilophytes. Conclusions Monophyly of monilophytes has been disputed on the basis of morphological and fossil evidence. In the context of a broad sampling of land plant data we find several new pieces of evidence for monilophyte monophyly. Results from this study demonstrate resolution among the four monilophytes lineages, albeit with moderate support; we posit a clade consisting of Equisetaceae and Psilotaceae that is sister to the true ferns, including Marattiaceae