Explore the vast range of titles available.

Ethylene/polar monomer coordination copolymerization offers an attractive way of making functionalized polyolefins. However, ethylene copolymerization with industrially relevant short chain length alkenoic acid remain a big challenge. Here we report the efficient direct copolymerization of ethylene with vinyl acetic acid by tetranuclear nickel complexes. The protic monomer can be extended to acrylic acid, allylacetic acid, ω-alkenoic acid, allyl alcohol, and homoallyl alcohol. Based on X-ray analysis of precatalysts, control experiments, solvent-assisted electrospray ionization-mass spectrometry detection of key catalytic intermediates, and density functional theory studies, we propose a possible mechanistic scenario that involves a distinctive vinyl acetic acid enchainment enabled by Ni···Ni synergistic effects. Inspired by the mechanistic insights, binuclear nickel catalysts are designed and proved much more efficient for the copolymerization of ethylene with vinyl acetic acid or acrylic acid, achieving the highest turnover frequencies so far for both ethylene and polar monomers simultaneously. The applications of polyolefins are limited by the nonpolar nature of the polymer. Here the authors show a method to copolymerize ethylene with the protic vinyl acetic acid via well defined multinuclear nickel catalysts.

Over the past century, significant progress in semipinacol rearrangement involving 1,2-migration of α-hydroxy carbocations has been made in the areas of catalysis and total synthesis of natural products. To access the α-hydroxy carbocation intermediate, conventional acid-mediated or electrochemical approaches have been employed. However, the photochemical semipinacol rearrangement has been underdeveloped. Herein, we report the organophotoredox-catalyzed semipinacol rearrangement via radical-polar crossover (RPC). A phenothiazine-based organophotoredox catalyst facilitates the generation of an α-hydroxy non-benzylic alkyl radical followed by oxidation to the corresponding carbocation, which can be exploited to undergo the semipinacol rearrangement. As a result, the photochemical approach enables decarboxylative semipinacol rearrangement of β-hydroxycarboxylic acid derivatives and alkylative semipinacol type rearrangement of allyl alcohols with carbon electrophiles, producing α-quaternary or α-tertiary carbonyls bearing sp 3 -rich scaffolds. Although electrochemical semipinacol rearrangements have been reported, a complementary photochemical route has yet to be developed. Here the authors report an organophotoredox-catalyzed semipinacol rearrangement via radical-polar crossover.

Transition metal catalysis plays a pivotal role in transforming unreactive C–H bonds. However, regioselective activation of distal aliphatic C–H bonds poses a tremendous challenge, particularly in the absence of directing templates. Activation of a methylene C–H bond in the presence of methyl C–H is underexplored. Here we show activation of a methylene C–H bond in the presence of methyl C–H bonds to form unsaturated bicyclic lactones. The protocol allows the reversal of the general selectivity in aliphatic C–H bond activation. Computational studies suggest that reversible C–H activation is followed by β-hydride elimination to generate the Pd-coordinated cycloalkene that undergoes stereoselective C–O cyclization, and subsequent β-hydride elimination to provide bicyclic unsaturated lactones. The broad generality of this reaction has been highlighted via dehydrogenative lactonization of mid to macro ring containing acids along with the C–H olefination reaction with olefin and allyl alcohol. The method substantially simplifies the synthesis of important bicyclic lactones that are important features of natural products as well as pharmacoactive molecules.Bicyclic lactones are valuable motifs for the synthesis of natural products and bioactive molecules. Now, a palladium-catalysed protocol has been developed to access unsaturated bicyclic lactones in one step from corresponding carboxylic acids. The method demonstrates reverse site selectivity for C(sp3)–H activation to form diverse bicyclic cores.

IARC periodically convenes such advisory groups to ensure that the agents evaluated in the Monographs are selected on the basis of the latest scientific evidence relevant to carcinogenicity.1 A detailed report of the Advisory Group recommendations will be published in due course.2 The Advisory Group assessed the response to a public call for nominations and considered more than 200 candidate agents, including the recommended priority agents remaining from a similar Advisory Group meeting convened in 2019.3 The Advisory Group comprised scientists with expertise across the spectrum of topics relevant to carcinogenicity. In drawing their conclusions, the members appraised, for each nominated agent, the evidence regarding human exposure, cancer in humans, cancer in experimental animals, and carcinogen mechanisms according to precepts described in the Preamble to the IARC Monographs.1 Systematic literature searches were complemented by a text mining and database fusion approach to identify relevant studies, document the relative abundance of literature for the different evidence streams, and map chemical similarity4 in support of decisions on prioritisation for individual agents and groups of agents. Monographs Advisory Group Members A Berrington de González (UK)—Meeting Chair; S A Masten (USA)—Meeting Vice Chair; P Bhatti (Canada); R T Fortner (Norway); S Peters (Netherlands); T Santonen (Finland); M G Yakubovskaya (Russian Federation)—Subgroup Meeting Chairs; R Barouki (France); S B M Barros (Brazil); D Barupal (USA); L E Beane Freeman (USA); G M Calaf (Chile); J Dillner (Sweden); K El Rhazi (Morocco); L Fritschi (Australia); S Fukushima (Japan); L Godderis (Belgium); M Kogevinas (Spain); D W Lachenmeier (Germany); D Mandrioli (Italy); M M Muchengeti (South Africa); R T Niemeier (USA); J J Pappas (Canada); J Pi (China); M P Purdue (USA); E Riboli (UK [unable to attend]); T Rodríguez (Nicaragua); V Schlünssen (Denmark) Declaration of interests All Monographs Advisory Group members declare no competing interests Invited Specialists None Representatives Y Choi, Division of Cancer Prevention, National Cancer Control Institute (South Korea);B Kim, Division of Cancer Prevention, National Cancer Control Institute (South Korea) Declaration of interests YC and BK declare no competing interests Observers R Bars, Regulatory Science Ltd (France); J Britt, ToxStrategies (USA) Declaration of interests RB is a a salaried employee of Regulatory Science Associates and CropLife International sponsored his travel to and attendance at the Advisory Group meeting. Rationale Agents not previously evaluated by IARC Monographs Disinfection byproducts in water, including haloacetic acids; sleep disruption; hair straightening products; metalworking fluids; obesity*; platinum-based chemotherapies as mechanistic class†; dibutyl phthalate; nitrogen dioxide‡; artificial light at night‡; sugar-sweetened beverage consumption‡; GLP-1 analogues‡; Fonofos‡ Relevant human cancer, animal cancer, and mechanistic evidence Fusobacterium nucleatum; human cytomegalovirus; sedentary behaviour; ultraprocessed food consumption; anthracyclines as mechanistic class†; BRAF inhibitors—dabrafenib, encorafenib, vemurafenib; epirubicin; tetracycline; tofacitinib and other Janus kinase inhibitors; perfluorohexanesulfonic acid; cannabis smoking‡; ultrafine particles‡; assisted reproductive techniques‡; chlorpyrifos‡ Relevant human cancer and mechanistic evidence Electronic nicotine delivery systems; estragole; carbadox; alachlor; cyfluthrin; cypermethrin; mancozeb; neonicotinoid insecticides; tebuconazole; vinclozolin; bisphenol A; bisphenol S; bisphenol F; 2,3-butanedione; carbon disulfide; diisononyl phthalate; glycidamide; hexafluoropropylene oxide dimer acid; methanol; ozone; pentabromodiphenyl ethers; triclosan; zearalenone‡ Relevant animal cancer and mechanistic evidence Hepatitis D virus; Salmonella typhi; taconite; terbufos‡ Relevant human cancer evidence Metyltetraprole; proquinazid; butyraldehyde; chlorinated paraffins; tris(chloropropyl)phosphate Relevant animal cancer evidence Methamphetamine; Congo red; cumyl hydroperoxide; 2,4-dihydroxybenzophenone; parabens; electronic waste work‡; polyhexamethyleneguanidine‡ Relevant mechanistic evidence Agents previously evaluated by IARC Monographs§ Hair colouring products (personal use of); coal dust; paracetamol (acetaminophen); textured implants (breast and buttock); carbaryl; ethylenedithiocarbamates; permethrin; pyrethrins and pyrethroids New human cancer, animal cancer, and mechanistic evidence to warrant re-evaluation of the classification Non-ionising radiation (radiofrequency)‡ New human cancer and animal cancer evidence to warrant re-evaluation of the classification Human papillomavirus β; Opisthorchis felineus; indoor combustion of biomass; textile manufacturing industry work; inorganic lead compounds; daunorubicin; doxorubicin; methotrexate; atrazine and other triazine pesticides; acetaldehyde; acrylamide; Merkel cell polyomavirus‡; clomiphene citrate‡; progestogen-only contraceptives‡; chlordecone‡ New human cancer and mechanistic evidence to warrant re-evaluation of the classification Multiwalled carbon nanotubes; butyl benzyl phthalate; 5-nitro-o-toluidine; 4-nitrotoluene; p-phenylenediamine New animal cancer and mechanistic evidence to warrant re-evaluation of the classification Metallic nickel; very hot beverages and food¶; carbon tetrachloride‡; tetrachloroethylene‡ New human cancer evidence to warrant re-evaluation of the classification Piperonyl butoxide New animal cancer evidence to warrant re-evaluation of the classification Schistosoma japonicum; Schistosoma mansoni; patulin; safrole; anaesthetics, volatile—isoflurane, sevoflurane, and desflurane; malathion; bromate compounds; 3,3′-dimethoxybenzidine; 3,3′-dimethylbenzidine; isoprene; fluoranthene‡ New mechanistic evidence to warrant re-evaluation of the classification Helicobacter pylori‡; aflatoxins‡; outdoor air pollution‡; tobacco smoking and second-hand smoke‡; silica dust‡; asbestos‡; hormone replacement therapy‡; radon and its decay products‡; ethylene oxide‡; formaldehyde† Group 1 carcinogen with evidence for new cancer sites (see section 3 of the Preamble to the IARC Monographs1) Table 1 Agents recommended for evaluation by the IARC Monographs with high priority Previous evaluation status Toxoplasma gondii; black cohosh extracts; outdoor combustion of biomass; tattoos and permanent make up; anatase-type nano-TiO2; neonatal phototherapy; anti-thymocyte globulin; bifenthrin; biphenyl; pendimethalin; α-pinene; sulfolane Agents not previously evaluated by the IARC Monographs Fumonisin B1; pyrrolizidine alkaloids; ingested nitrate; selenium and selenium compounds; xylenes Agents previously evaluated by the IARC Monographs* Table 2 Agents recommended for evaluation by the IARC Monographs with medium priority Rationale Chronic circadian dysfunction; diabetes; insomnia; reduction of sex hormones with human aging; violation of tissue renewal or regeneration with human aging; alefacept No evidence of exposure, or not an exogenous exposure Dysbiotic microbiota; poor oral hygiene; nitrate-reducing bacteria in tobacco; SARS-CoV-2; cleaning products; long working hours; social isolation and loneliness; phosphorescent paints; laboratory work and occupation as a chemist; occupation as a pesticide applicator; semiconductor industry work; acrylonitrile-butadiene-styrene particles emitted by three-dimensional printers; engineered stone fabrication; microplastics and nanoplastics; aluminium; rare earth elements; intense pulsed light; artificially sweetened beverage consumption; dietary salt intake; indole-3-carbinol; isoflavones; sucralose; gadolinium-based contrast agents; gene or cell therapy or vectors; glucocorticoids; glutathione; reversible acetylcholinesterase inhibitors; allyl alcohol; ametryn; atraric acid; boscalid; o-benzyl-p-chlorophenol; cinidon ethyl; p-cresol; 1,2-cyclohexanedicarboxylic acid, diisononyl ester; 2,4-dichlorophenol; 2,4-dimethylphenol; ethyl anthranilate; S-ethyl-N,N-dipropylthiocarbamate; furmecyclox; hexythiazox; 2-hydroxy-4-methoxybenzophenone; menthyl anthranilate; methyl anthranilate; palmitic acid; phosmet; red dye number 3 (erythrosine); styrene-acrylonitrile (SAN) trimer; 2,4,6-tribromophenol

A new type of catalyst containing magnesium oxide modified with various modifiers ranging from bromine and iodine, to interhalogen compounds, hydrohalogenic acids, and alkyl halides have been prepared using chemical vapor deposition (CVD) and wet impregnation methods. The obtained systems were characterized using a number of methods: determination of the concentration of X− ions, surface area determination, powder X-ray diffraction (PXRD), surface acid–base strength measurements, TPD of probe molecules (acetonitrile, pivalonitrile, triethylamine, and n-butylamine), TPD-MS of reaction products of methyl iodide with MgO, and Fourier transform infrared spectroscopy (FTIR). The catalysts’ activity and chemoselectivity during transfer hydrogenation from ethanol to acrolein to allyl alcohol was measured. A significant increase in the activity of modified MgO (up to 80% conversion) in the transfer hydrogenation of acrolein was found, while maintaining high chemoselectivity (>90%) to allyl alcohol. As a general conclusion, it was shown that the modification of MgO results in the suppression of strong basic sites of the oxide, with a simultaneous appearance of Brønsted acidic sites on its surface. Independently, extensive research on the reaction progress of thirty alkyl halides with MgO was also performed in order to determine its ability to neutralize chlorinated wastes.

We report here an efficient method for targeted mutagenesis of Arabidopsis genes through regulated expression of zinc finger nucleases (ZFNs)—enzymes engineered to create DNA double-strand breaks at specific target loci. ZFNs recognizing the Arabidopsis ADH1 and TT4 genes were made by Oligomerized Pool ENgineering (OPEN)—a publicly available, selection-based platform that yields high quality zinc finger arrays. The ADH1 and TT4 ZFNs were placed under control of an estrogen-inducible promoter and introduced into Arabidopsis plants by floral-dip transformation. Primary transgenic Arabidopsis seedlings induced to express the ADH1 or TT4 ZFNs exhibited somatic mutation frequencies of 7% or 16%, respectively. The induced mutations were typically insertions or deletions (1—142 bp) that were localized at the ZFN cleavage site and likely derived from imprecise repair of chromosome breaks by nonhomologous end-joining. Mutations were transmitted to the next generation for 69% of primary transgenics expressing the ADH1 ZFNs and 33% of transgenics expressing the TT4 ZFNs. Furthermore, ≈20% of the mutant-producing plants were homozygous for mutations at ADH1 or TT4, indicating that both alleles were disrupted. ADH1 and TT4 were chosen as targets for this study because of their selectable or screenable phenotypes (adh1, allyl alcohol resistance; tt4, lack of anthocyanins in the seed coat). However, the high frequency of observed ZFN-induced mutagenesis suggests that targeted mutations can readily be recovered by simply screening progeny of primary transgenic plants by PCR and DNA sequencing. Taken together, our results suggest that it should now be possible to obtain mutations in any Arabidopsis target gene regardless of its mutant phenotype.

A pair of primers was designed to amplify the propylene alcohol dehydrogenase gene sequence based on the cDNA sequence of the tobacco allyl-alcohol dehydrogenase gene. All introns were sequenced using traditional polymerase chain reaction (PCR) methods and T-A cloning. The sequences from common tobacco (Nicotiana tabaccum L.) and rustica tobacco (Nicotiana rustica L.) were analysed between the third intron and the fourth intron of the propylene alcohol dehydrogenase gene. The results showed that the alcohol dehydrogenase gene is a low-copy nuclear gene. The intron sequences have a combination of single nucleotide polymorphisms and length polymorphisms between common tobacco and rustica tobacco, which are suitable to identify the different germplasms. Furthermore, there are some single nucleotide polymorphism sites in the target sequence within common tobacco that can be used to distinguish intraspecific varieties.

Transesterification of dialkyl carbonates with allyl alcohol in the presence of bases afforded a mixture of alkyl allyl carbonate and diallyl carbonate. Dimethyl carbonate was found to be the most reactive and was used to obtain both unsymmetric allyl methyl carbonate and symmetric diallyl carbonate. Sodium and potassium alkoxides were more efficient catalysts for the transesterification compared to the corresponding hydroxides. The highest degree of transesterification of dimethyl carbonate (69%) was achieved using sodium alkoxide as a catalyst.

In the present study, an epoxy compound, 1,2‐epoxy‐6‐methyl‐triglycidyl‐3,4,5‐cyclohexanetricarboxylate (EGCHC) synthesized from sorbic acid, maleic anhydride, and allyl alcohol is proposed. Using commodity chemicals, a bio‐based carbon content of 68.4 % for the EGCHC resin is achieved. When cured with amine hardeners, the high oxirane content of EGCHC forms stiff cross‐linked networks with strong mechanical and thermal properties. The characterization of the epoxy specimens showed that EGCHC can compete with conventional epoxy resins such as DGEBA. A maximum stiffness of 3965 MPa, tensile strength of 76 MPa, and T g of 130 °C can be obtained by curing EGCHC with isophorone diamine (IPD). The cured resin showed to be decomposable under mild conditions due to the ester bonds. The solid material properties of EGCHC expose its potential as a promising bisphenol A, and epichlorohydrine free alternative to conventional petroleum‐based epoxies with an overall high bio‐based carbon content.

A highly efficient asymmetric allylic alkylation of cyclic and acyclic carbon nucleophiles with vinyl epoxides has been developed, which exhibits good functional group compatibility, high atomic and step economy. This protocol utilizes a strategy of synergistic catalysis with a chiral N , N ′-dioxide/Ni II complex and an achiral Pd 0 catalyst, generating a series of multi-substituted allylic alcohols with a quaternary carbon stereocenter in high yield and excellent regio-, Z / E - and enantioselectivity under mild conditions. Further transformations of the product demonstrate the potential utility of this protocol in the synthesis of allyl alcohol derivatives and natural product analogues. Experimental studies revealed that the N , N ′-dioxide/metal complexes play an important role in controlling the Z / E - and enantioselectivity. The density functional theory (DFT) calculations further demonstrated that multiple C-H···π interactions between the aromatic rings of the two substrates and the amide moiety in the ligand stabilized the dominant transition state.