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https://www.readbyqxmd.com/read/28812346/metal-free-synthesis-of-2-aminobenzothiazoles-via-iodine-catalyzed-and-oxygen-promoted-cascade-reactions-of-isothiocyanatobenzenes-with-amines
#1
Yuanshuang Xu, Bin Li, Xinying Zhang, Xuesen Fan
In this paper, a highly efficient and sustainable synthesis of 2-aminobenzothiazoles through the cascade reactions of isothiocyanatobenzenes with primary or secondary amines by using iodine as a catalyst and oxygen as an oxidant is presented. Mechanistically, the formation of the title compounds involves the in situ formation of the required benzothiourea intermediate followed by its intramolecular cross dehydrogenative coupling of a C(sp2)-H bond and a S-H bond. To our knowledge, this should be the first example in which 2-aminobenzothiazoles are efficiently prepared from simple and cheap isothiocyanates and amines under metal free conditions by using iodine as a catalyst and molecular oxygen as an oxidant with water as the byproduct...
August 16, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28812088/consecutive-reduction-radical-cyclization-and-oxidative-dehydrogenation-reaction-of-ortho-substituted-diboryl-compounds
#2
Lirong Yu, Yanglizhi Li, Xi Wang, Xingyong Wang, Panpan Zhou, Shangda Jiang, Xiaobo Pan
An elegant synthetic route to a ladder-type di-borate compound 2a was reported based on the reduction, radical-cyclization, and oxidative-dehydrogenation reaction of 1. The existence of the biradical intermediate [1˙˙]2- was supported by both EPR measurements and DFT calculations.
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28809505/relay-catalysis-manganese-iii-phosphate-catalyzed-asymmetric-addition-of-%C3%AE-dicarbonyls-to-ortho-quinone-methides-generated-by-catalytic-aerobic-oxidation
#3
Konrad Gebauer, Franziska Reuß, Matthias Spanka, Christoph Schneider
The combination of an in situ formed MnL3 complex (HL = Hacac or R(C═O)CH2CO2R) and a chiral phosphoric acid HX* allows for a fully catalytic, asymmetric synthesis of 4H-chromenes starting from 2-alkyl-substituted phenols. The aerobic oxidation toward a transient ortho-quinone methide was efficiently catalyzed by a manganese(III) species MnL3 while the ensuing Michael addition of β-dicarbonyl compounds proved to be catalyzed by a chiral manganese phosphate MnL2X*.
August 15, 2017: Organic Letters
https://www.readbyqxmd.com/read/28806081/chlorination-kinetics-of-11-nor-9-carboxy-%C3%AE-9-tetrahydrocannabinol-effects-of-ph-and-humic-acid
#4
Allison L Mackie, Yuri Park, Graham A Gagnon
The main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), and its metabolites are emerging organic contaminants that have been detected in waste and surface waters. As legalization of marijuana for medical and recreational use continues, the effects of increased use and potency of marijuana on water and wastewater treatment processes and the environment should be considered. This study examined degradation kinetics of the main urinary metabolite of THC, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) with chlorine...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806067/immunosensor-employing-stable-solid-1-amino-2-naphthyl-phosphate-and-ammonia-borane-toward-ultrasensitive-and-simple-point-of-care-testing
#5
Jeongwook Seo, Hyeri Ha, Seonhwa Park, Al-Monsur Jiaul Haque, Sinyoung Kim, Jung Min Joo, Haesik Yang
Biosensors for ultrasensitive point-of-care testing require dried reagents with long-term stability and a high signal-to-background ratio. Although ortho-substituted diaromatic dihydroxy and aminohydroxy compounds undergo fast redox reactions, they are not used as electrochemical signaling species because they are readily oxidized and polymerized by dissolved oxygen. In this report, stable, solid 1-amino-2-naphthyl phosphate (1A2N-P) and ammonia-borane (H3N-BH3) are respectively employed as a substrate for alkaline phosphatase (ALP) and a reductant for electrochemical-chemical (EC) redox cycling...
August 14, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28805855/rhodium-iii-catalyzed-and-meoh-involved-regioselective-mono-alkenylation-of-n-arylureas-with-acrylates
#6
Honggui Lv, Jingjing Shi, Junjun Huang, Chao Zhang, Wei Yi
We herein disclose, for the first time, Rh(iii)-catalyzed and MeOH-involved regioselective mono-alkenylation of arenes with acrylates using NHCONMe2 as the transformable directing group, giving direct access to diverse ortho-acrylated N-phenyl carbamates. The synthetic application of the obtained products to build privileged quinolin-2(1H)-ones and 3-(2-aminophenyl)acrylates has also been demonstrated in subsequent derivatization reactions.
August 14, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28805836/dinuclear-zinc-complex-catalyzed-asymmetric-methylation-and-alkynylation-of-aromatic-aldehydes
#7
Shanshan Liu, Gao-Wei Li, Xiao-Chao Yang, De-Yang Zhang, Min-Can Wang
A general AzePhenol dinuclear zinc catalytic system has been successfully developed and introduced into the asymmetric addition of dimethylzinc and alkynylzinc to aromatic aldehydes. In this system, an azetidine derived chiral ligand has proven to be an effective enantioselective promoter. Under the optimal reaction conditions, a series of chiral 1-hydroxyethyl (up to 99% ee) and secondary propargylic alcohols (up to 96% ee) were generated with good yields and enantioselectivities. Additionally, this novel catalytic system showed good functional group compatibility...
August 14, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28805383/cu-ii-catalyzed-ortho-selective-aminomethylation-of-phenols
#8
Jin-Ling Dai, Nan-Qi Shao, Jin Zhang, Run-Ping Jia, Dong-Hui Wang
A Cu(II)-catalyzed ortho-selective functionalization of free phenols with trifluoroborates to afford Csp2-Csp3 coupling products under mild conditions has been developed. A variety of functional groups on the phenol and the potassium ami-nomethyltrifluoroborate substrates were found compatible, fur-nishing the corresponding products in moderate to excellent yields. A single-electron transfer radical coupling mechanism involving a six-membered transition state is proposed to rationalize the high levels of ortho-selectivity in the reaction...
August 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28803804/effect-of-esthetic-coating-on-surface-roughness-of-orthodontic-archwires
#9
Seyed Mohammad Mousavi, Milad Shamohammadi, Zahra Rastegaar, Masoumeh Skini, Vahid Rakhshan
BACKGROUND AND AIM: Esthetic wires are commonly used in orthodontic treatments. Surface roughness is an important factor in the friction and bacterial adhesion in these wires. Surface roughness of esthetic wires has not been assessed, except in a few recent (mostly qualitative esthetics) studies. The aim of this study was to quantitatively compare the surface roughness of 4 coated esthetic wires with that of a conventional orthodontic wire. MATERIALS AND METHODS: In this in vitro trial, 25 coated and uncoated orthodontic archwires were studied, including: NiTi Memory wire (American Orthodontics, USA) as a control group; Orthocosmetic Elastinol (Ortho Organizers, USA); Perfect (Hubit, Korea); Imagination (Gestenco, Sweden); EverWhite (American Orthodontics, USA)...
August 10, 2017: International Orthodontics
https://www.readbyqxmd.com/read/28800239/rh-i-catalyzed-alkylation-of-ortho-c-h-bonds-in-aromatic-amides-with-maleimides
#10
Qiyuan He, Takuma Yamaguchi, Naoto Chatani
An alkylation of C-H bonds with maleimides by a rhodium-catalyzed reaction of aromatic amides containing an 8-aminoquinoline moiety as the directing group is reported. Various N-substituents in the maleimide, including methyl, ethyl, cyclohexyl, benzyl, and phenyl groups and even H, are applicable to the reaction. The reaction is highly regioselective at the less hindered ortho-C-H bond when meta-substituted aromatic amides are used as substrates.
August 11, 2017: Organic Letters
https://www.readbyqxmd.com/read/28799951/surface-engineered-blood-adsorption-device-for-hyperphosphatemia-treatment
#11
Quan Shi, Michael Jolly, Marian G Mccord, Melanie S Joy
Correspondence: Melanie S. Joy, PharmD, PhD, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Mail Stop C238, Room V20-4108, 12850 East Montview Blvd, Aurora, CO 80045. Email: Melanie.Joy@ucdenver.eduThe research employed surface engineering methods to develop, optimize, and characterize a novel textile-based hemoadsorption device for hyperphosphatemia in hemodialysis-dependent end-stage kidney disease. Phosphate adsorbent fabrics (PAFs) were prepared by thermopressing alumina powders to polyester filtration fabrics and treatment with trimesic acid (TMA)...
August 8, 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/28799765/benzylic-c-h-trifluoromethylation-via-photoenol
#12
Takafumi Ide, Shuya Masuda, Yuji Kawato, Hiromichi Egami, Yoshitaka Hamashima
Photoenols generated in situ from ortho-methyl-substituted phenylketones such as benzophenones and acetophenones were trifluoromethylated with Togni reagent without any additive or catalyst. This trifluoromethylation reaction proceeded smoothly under photoirradiation conditions (365 nm). Various functional groups were tolerant of the reaction conditions. Interestingly, the trifluoromethyl group was exclusively introduced at the ortho-benzylic position. Mechanistic studies suggested that this reaction proceeds via formation of a photoenol, not via a radical pathway...
August 11, 2017: Organic Letters
https://www.readbyqxmd.com/read/28799217/divergent-ch-annulation-for-multi-fused-n-heterocycles-regio-and-stereospecific-cyclizations-of-n-alkynylindoles
#13
Khyarul Alam, Sung Won Hong, Kyung Hwan Oh, Jin Kyoon Park
N-Alkynylindoles were divergently cyclized for the synthesis of multi-fused N-heterocycles. An ortho-aryl palladium species was added to the -position of an ynamine to generate (Z)-6-alkylidene/benzylidene-6H-isoindolo[2,1-a]indoles, while Pt-catalyzed -addition via -activation gave 5-alkyl/arylindolo[2,1-a]isoquinolines. Double cyclizations using PdCl2 and oxidant afforded bright yellow benzo[7,8]indolizino[2,3,4,5-ija]quinolines, the synthesis of which was also demonstrated in a different synthetic route...
August 11, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28792660/photochemical-intramolecular-c-h-addition-of-dimesityl-hetero-arylboranes-via-a-1-6-sigmatropic-rearrangement
#14
Naoki Ando, Aiko Fukazawa, Tomokatsu Kushida, Yoshihito Shiota, Shuhei Itoyama, Kazunari Yoshizawa, Yasunori Matsui, Yutaro Kuramoto, Hiroshi Ikeda, Shigehiro Yamaguchi
A new reaction mode for triarylboranes under photochemical conditions was discovered. Photoirradiation of dimesitylboryl-substituted (hetero)arenes produced spirocyclic boraindanes, where one of the C-H bonds in the ortho-methyl groups of the mesityl substituents was formally added in a syn fashion to a C-C double bond of the (hetero)aryl group. Quantum chemical calculations and laser flash photolysis measurements indicated that the reaction proceeds via a [1,6]-sigmatropic rearrangement. This behavior is reminiscent of the photochemical reaction mode of arylalkenylketones, demonstrating the isosteric relation between tricoordinate organoboron compounds and the corresponding pseudo-carbocationic species in terms of pericyclic reactions...
August 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28783416/toluene-and-methylethylketone-effect-of-combined-exposure-on-their-metabolism-in-rat
#15
Frédéric Cosnier, Hervé Nunge, Élodie Bonfanti, Stéphane Grossmann, Anne-Marie Lambert-Xollin, Samuel Muller, Sylvie Sébillaud, Aurélie Thomas, Laurent Gaté, Pierre Campo
Multiple exposures are ubiquitous in industrial environments. In this article, we highlight the risks faced by workers and complete the data available on the metabolic impact of a common mixture: toluene (TOL) and methylethylketone (MEK). Rats were exposed by inhalation under controlled conditions either to each solvent individually, or to mixtures of the two. How the interaction between the two solvents affected their fate in the blood and brain, their main relevant urinary metabolites (o-cresol, benzylmercapturic acid for TOL and 2,3-butanediols for MEK) and their hepatic metabolism were investigated...
August 7, 2017: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/28780453/a-novel-horizontal-subsurface-flow-constructed-wetland-reducing-area-requirements-and-clogging-risk
#16
Triantafyllos Tatoulis, Christos S Akratos, Athanasia G Tekerlekopoulou, Dimitrios V Vayenas, Alexandros I Stefanakis
The use of Constructed Wetlands (CWs) has been nowadays expanded from municipal to industrial and agro-industrial wastewaters. The main limitations of CWs remain the relatively high area requirements compared to mechanical treatment technologies and the potential occurrence of the clogging phenomenon. This study presents the findings of an innovative CW design where novel materials were used. Four pilot-scale CW units were designed, built and operated for two years. Each unit consisted of two compartments, the first of which (two thirds of the total unit length) contained either fine gravel (in two units) or random type high density polyethylene (HDPE) (in the other two units)...
August 1, 2017: Chemosphere
https://www.readbyqxmd.com/read/28780150/exploration-of-aroyl-heteroaroyl-iminothiazolines-featuring-2-4-5-trichlorophenyl-moiety-as-a-new-class-of-potent-selective-and-in-vitro-efficacious-glucosidase-inhibitors
#17
Madiha Kazmi, Sumera Zaib, Sayyeda Tayyeba Amjad, Imtiaz Khan, Aliya Ibrar, Aamer Saeed, Jamshed Iqbal
A series of iminothiazolines (4a-j) featuring 2,4,5-trichlorophenyl moiety and aroyl/heteroaroyl substituents has been prepared from readily accessible thioureas. In-vitro screening against glucosidase enzymes showed highly specific inhibition of α-glucosidase with a marked dependence of the potency upon the nature of the aroyl/heteroaroyl substituents. The most potent representatives, bearing ortho-tolyl and bulky naphthyl groups displayed the highest inhibitory potential with IC50 value of 0.15±0.01µM compared to standard drug acarbose (IC50=38...
July 25, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/28777094/in-crystallo-activity-tests-with-latent-apple-tyrosinase-and-two-mutants-reveal-the-importance-of-the-mutated-sites-for-polyphenol-oxidase-activity
#18
Ioannis Kampatsikas, Aleksandar Bijelic, Matthias Pretzler, Annette Rompel
Tyrosinases are type 3 copper enzymes that belong to the polyphenol oxidase (PPO) family and are able to catalyze both the ortho-hydroxylation of monophenols and their subsequent oxidation to o-quinones, which are precursors for the biosynthesis of colouring substances such as melanin. The first plant pro-tyrosinase from Malus domestica (MdPPO1) was recombinantly expressed in its latent form (56.4 kDa) and mutated at four positions around the catalytic pocket which are believed to influence the activity of the enzyme...
August 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28776516/intricacies-of-ligand-coordination-in-tricarbonylchromium-0-complexes-with-ortho-and-para-fluorobiphenyls
#19
Ilia A Guzei, Lara C Spencer, Sondra C Buechel, Leah B Kaufmann, Curtis J Czerwinski
The steric and electronic factors that influence which of the two rings of a substituted biphenyl ligand coordinates to chromium are of interest and it has been suggested that haptotropic rearrangements within these molecules may be limited if the arene-arene dihedral angle is too large. Two tricarbonylchromium(0) complexes and their respective free ligands have been characterized by single-crystal X-ray diffraction. In the solid state, tricarbonyl[(1',2',3',4',5',6'-η)-2-fluoro-1,1'-biphenyl]chromium(0), [Cr(C12H9F)(CO)3], (I), exists as the more stable isomer with the nonhalogenated arene ring ligated to the metal center...
August 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28766860/hydroarylation-of-2-aryloxybut-1-en-3-ynes-via-pd-acid-catalyzed-c-h-bond-activation-concise-synthesis-of-2-3-bismethylene-2-3-dihydrobenzofurans
#20
Yasunori Minami, Migumi Sakai, Takumi Sakamaki, Tamejiro Hiyama
We found an intramolecular exo-hydroarylation of 2-aryloxy-1,4-disilylbut-1-en-3-ynes via ortho-C-H bond activation under palladium(0) and acid catalysis to give 2,3-bis(silylmethylidene)-2,3-dihydrobenzofurans. The two silyl groups probably promote the reaction and play a key role in stabilizing the diene moiety in the product. The products are readily led to functionalized condensed cycles by the Diels-Alder reaction.
August 2, 2017: Chemistry, An Asian Journal
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