journal
https://read.qxmd.com/read/38328000/semisynthesis-characterization-and-biological-evaluation-of-fluorinated-analogues-of-the-spirobisnaphthalene-diepoxin-%C3%AE
#1
JOURNAL ARTICLE
Hadi Pourhadi, Tamam El-Elimat, Manuel Rangel-Grimaldo, Tyler N Graf, Joseph O Falkinham, Manead Khin, Joanna E Burdette, Nathan Mirtallo Ezzone, Jonathan Jeyaraj, Esperanza Carcache de Blanco, Cedric J Pearce, Nicholas H Oberlies
Diepoxin-η ( 1 ) is a cytotoxic fungal metabolite belonging to the spirobisnaphthalene structural class. In this study, four mono fluorinated analogues ( 2 - 5 ) of diepoxin-η ( 1 ) were semisynthesized in a single-step by selectively fluorinating the naphthalene moiety with Selectfluor. The structures of 2-5 were elucidated using a set of spectroscopic and spectrometric techniques and were further confirmed by means of TDDFT-ECD and isotropic shielding tensors calculations. Compounds 2-5 showed equipotent cytotoxic activity to 1 when tested against OVCAR3 (ovarian) and MDA-MB-435 (melanoma) cancer cell lines with IC50 values that range from 5...
January 12, 2024: Tetrahedron Letters
https://read.qxmd.com/read/38009110/4-isocyanoindole-2-deoxyribonucleoside-4icin-an-isomorphic-indole-nucleoside-suitable-for-inverse-electron-demand-diels-alder-reactions
#2
JOURNAL ARTICLE
Kellan T Passow, Daniel A Harki
Isomorphic nucleosides are powerful tool compounds for interrogating a variety of biological processes involving nucleosides and nucleic acids. We previously reported a fluorescent isomorphic indole nucleoside called 4CIN . A distinguishing molecular feature of 4CIN is the presence of a 4-cyano moiety on the indole that functions as the nucleobase. Given the known chemical reactivity of isonitriles with tetrazines through [4+1]-cycloaddition chemistry, we investigated whether conversion of 4CIN to the corresponding isonitrile would confer a useful chemical probe...
November 30, 2023: Tetrahedron Letters
https://read.qxmd.com/read/38371912/the-full-spectrum-tuning-of-fluorescent-molecules-via-a-one-pot-multicomponent-reaction
#3
JOURNAL ARTICLE
Nathan Bedard, Addison G Coen, Scott Pekarske, Andrew Sennett, Garrett J Davis, Timothy Chavez, Dennis L Lichtenberger, Christopher Hulme
Fluorogenic probes for imaging enable visualization and analysis of difficult-to-reach cells and organelles. However, there are limited efficient examples of tuning these fluorescent molecules to higher wavelengths. This is vital since different tissues are sensitive to varying wavelength emissions. To address this need, we report the discovery, tuning, structure-photophysical property relationships (SPPR), and time-dependent DFT (TD-DFT) computations of 400-700+ nm fluorescent pyrido[2',1':2,3]imidazo[4,5-c]isoquinolines and substituted imidazo[1,2-a]pyridin-3-amines...
October 25, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37860707/computational-study-of-an-oxetane-4-h-pyrazole-as-a-diels-alder-diene
#4
JOURNAL ARTICLE
Brian J Levandowski, Nile S Abularrage, Brian J Graham, Ronald T Raines
We combine the effects of spirocyclization and hyperconjugation to increase the Diels-Alder reactivity of the 4 H -pyrazole scaffold. A density functional theory (DFT) investigation predicts that 4 H -pyrazoles containing an oxetane functionality at the saturated center are extremely reactive despite having a relatively high-lying lowest unoccupied molecular orbital (LUMO) energy.
October 25, 2023: Tetrahedron Letters
https://read.qxmd.com/read/38343394/synthesis-of-the-hypoxia-inducible-factor-2-%C3%AE-hif-2-%C3%AE-inhibitor-3-1-s-2-s-3-r-2-3-difluoro-1-hydroxy-7-methylsulfonylindan-4-yl-oxy-5-fluorobenzonitrile-pt2977-belzutifan-efficient-replication-of-established-approaches
#5
JOURNAL ARTICLE
Khagendra B Hamal, Cyprian I Pavlich, Graham J Carlson, Yu Ching Wong, Fangzhou Zhao, Qing Zhang, Kevin K Klausmeyer, Kevin G Pinney
A concise linear synthesis of hypoxia inducible factor-2 α (HIF-2 α ) inhibitor, belzutifan was achieved by reproducing key components of previous synthetic approaches to this molecule as described in several publications and patents. Belzutifan is an orally bioavailable small-molecule (HIF-2 α ) inhibitor for the treatment of von Hippel-Lindau (VHL) disease-associated renal cell carcinoma (RCC) that received FDA approval in 2021. Herein, we report a 13-step synthesis of PT2977 that proceeded in good overall yield with high diastereoselectivity...
September 19, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37841749/palladium-catalyzed-allylation-of-2-and-4-alkylpyridines-via-n-allyl-alkylidene-dihydropyridine-intermediates
#6
JOURNAL ARTICLE
Grant N Shivers, F Christopher Pigge
A method to introduce allyl or cinnamyl groups to the picolyl positions of 2- or 4-alkylpyridines is described. Substituted N-allyl pyridinium salts are first treated with base (KOt Bu) followed by catalytic [(η3 -allyl)PdCl]2 and PPh3 to result in formal Pd-catalyzed transfer of N-allyl groups to the pyridine periphery. The reaction is believed to proceed through initial formation of nucleophilic alkylidene dihydropyridine intermediates that react with (π-allyl)Pd(II) electrophiles, thereby regenerating N-allyl pyridinium cations...
September 19, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37449084/enantioselective-radical-cascade-cyclization-via-ti-catalyzed-redox-relay
#7
JOURNAL ARTICLE
Peng Yu, Wen Zhang, Song Lin
Radical cascade cyclization reactions provide an efficient method for the construction of polycyclic architectures with multiple stereogenic centers. However, achieving enantioselectivity control of this type of reaction is a challenging task. Here, we report an enantioselective cyclization of polyfunctional aryl cyclopropyl ketone and alkyne units, wherein the stereochemical outcome is directed by a chiral Ti(salen) catalyst. This transformation was proposed to proceed via a radical cascade process involving the reductive ring-opening of the cyclopropyl ketone followed by two annulation events entailing cyclization of the ensuing alkyl radical onto the alkyne and subsequent addition of the incipient vinyl radical to the Ti(IV)-enolate...
July 28, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37694227/sodium-trifluoroacetate-mediated-copper-catalyzed-aza-michael-addition-of-%C3%AE-%C3%AE-unsaturated-olefins-with-aromatic-amines
#8
JOURNAL ARTICLE
S Erfan Masaeli, Mohsen Teimouri, Bhupendra Adhikari, Mahshid Attarroshan, James W Akin, Selvam Raju, Sean L Stokes, Joseph P Emerson
We present a sodium trifluoroacetate (CF3 CO2 Na) mediated copper-catalyzed aza -Michael addition of aromatic amines with activated olefins under mild, aqueous reaction conditions. This simplistic protocol employs a copper catalyst (10 mol%) and water as solvent. This transformation occurs precisely with aromatic substituted amines containing both electron-donating (EDG) and electron-withdrawing (EWG) groups. A broad range of substrates were tested under the optimized conditions, which are producing good to moderate yields...
June 6, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37334260/potassium-carbonate-mediated-%C3%AE-selective-anomeric-o-alkylation-with-primary-electrophiles-application-to-the-synthesis-of-glycosphingolipids
#9
JOURNAL ARTICLE
Ishani Lakshika Hettiarachchi, Fenglang Wu, Maria Stoica, Xiaohua Li, Jianglong Zhu
Stereoselective construction of a variety of β-glycosides can be achieved using abundant and inexpensive K2 CO3 -mediated stereoselective anomeric O-alkylation of sugar lactols with primary electrophiles. In addition, application of this methodology to the synthesis of various azido-modified glycosphingolipids has been accomplished in good yields and excellent anomeric selectivity using sphingosine-derived primary triflate.
June 6, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37274138/synthesis-of-2-3-disubstituted-pyrroles-by-lewis-acid-promoted-cyclization-of-n-sulfonyl-vinylogous-carbamates-and-amides
#10
JOURNAL ARTICLE
Gavin J Rustin, Matthew G Donahue
A three-step sequence to construct pyrroles from three components including 2,2-dimethoxyethylamine, aryl/alkyl sulfonyl chlorides and alkynes bearing electron-withdrawing groups is presented. The pyrroles are proposed to arise via a 5- exo -trig cyclization proceeding through both oxocarbenium and N -sulfonyliminium ions. This modular route allows for the variability at the N -sulfonyl group, the C2 and C3 substituents for rational vectoring of the pyrrole nucleus for downstream processes.
June 6, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37274137/stereoselective-synthesis-of-photoactivatable-man-%C3%AE-1-4-glcnac-based-bioorthogonal-probes
#11
JOURNAL ARTICLE
Abdullah A Hassan, Mia L Huang
We report an operationally facile protocol to prepare photoactivatable probes of the bioactive mammalian disaccharide, Man(β1,4)GlcNAc. Using conformationally restricted mannosyl hemi-acetal donors in a one-pot chlorination, iodination and glycosylation sequence, β-mannosides were generated in excellent diastereoselectivities and yields. Upon accessing the disaccharide, we generated the corresponding photoactivatable probes by appending a diazirine-alkyne equipped linker via a condensation reaction between a diazirine-containing linker and C-1 and C-2 derivatized mannosylamines to furnish the desired C-1 and C-2 modified Man(β1,4)GlcNAc-based probes...
June 6, 2023: Tetrahedron Letters
https://read.qxmd.com/read/38505129/recent-advances-in-base-metal-catalyzed-cooperative-transfer-hydrogenation-and-hydrodeuteration-of-alkenes
#12
JOURNAL ARTICLE
Hai N Tran, Julian G West
Catalytic alkene hydrogenation is a powerful method that has been widely used in the syntheses of valuable products ranging from commodity chemicals to pharmaceuticals. Hydrogenation has also been a key strategy for selectively introducing heavy hydrogen isotopes to small molecules, a key strategy for metabolism studies and even the synthesis of "heavy drugs," where the hydrogen isotope is a key element of the active pharmaceutical ingredient. Traditional hydrogenations with pressurized H2 gas are atom economic but often require complex reaction setups or expensive metal catalysts...
March 24, 2023: Tetrahedron Letters
https://read.qxmd.com/read/36936473/efficient-syntheses-of-kls-13019-using-palladium-mediated-cross-couplings
#13
JOURNAL ARTICLE
William A Kinney, Mark E McDonnell, Stanley Freeman, Nick Simons, Chao Han, Lanyi Yang
KLS-13019 is a structural analogue of cannabidiol, that shows improved bioavailability and potency in both preventing and reversing paclitaxel-induced neurotoxicity in vitro and in vivo. KLS-13019 was selected as a development candidate and attention was turned to development of a scalable synthesis. The original synthesis of KLS-13019 was not efficient, regioselective, or high yielding. Two new syntheses are reported that make use of the palladium catalyzed cross couplings to a chemically advanced intermediate 5 , dramatically shortening (3-4 steps) and improving the overall yield...
March 6, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37333936/preparation-of-%C3%AE-hydroxyketones-aldols-from-the-alkylation-of-o-silyl-aryl-cyanohydrins-with-epoxides
#14
JOURNAL ARTICLE
Lissa D Gilreath, Diamond R Melendez, Caylie A McGlade, Jennifer E Shoemaker, Dakoda W Mullinax, Aaron M Hartel
β-Hydroxyketones (aldols) are prepared from the alkylation-deprotection of O -silylated aryl cyanohydrins with epoxides. Key to the success of the method was the suppression of an in situ cyclic imidate formation that occurs upon initial opening of the epoxide ring.
February 17, 2023: Tetrahedron Letters
https://read.qxmd.com/read/36777739/total-synthesis-of-%C3%A2-n-methyldibromoisophakellin-and-n-methylugibohlin-via-net-3-2-cycloguanidinylations-employing-2-amido-1-3-diamino-allyl-cations
#15
JOURNAL ARTICLE
Nobuyuki Matsumoto, Taehwan Hwang, Daniel Romo
A concise total synthesis of (±)- N -methyldibromoisophakellin, a member of the monomeric pyrrole-aminoimidazole alkaloid family isolated from the marine sponge Stylissa carbica , was achieved via a net [3+2] cycloaddition to install the cyclic guanidine. This ring annulation employs a 2-amido-1,3-aminoallyl cation obtained under oxidative conditions from variously N -substituted guanidines which in one instance led to isolation of a tetracycle bearing a carbinolamine center through subsequent benzylic oxidation...
January 31, 2023: Tetrahedron Letters
https://read.qxmd.com/read/37521200/conjugate-reduction-of-vinyl-bisphosphonates
#16
JOURNAL ARTICLE
Nyema M Harmon, Nathaniel R Gehrke, David F Wiemer
Vinyl bisphosphonates can be readily prepared by condensation of an aromatic aldehyde with the tetraester of a methylenebisphosphonate, and reduction of the resulting olefin is an attractive strategy for the preparation of monoalkyl geminal bisphosphonates. Conjugate reduction through use of variations on the Stryker approach has proven to be an efficient method for that reduction, even in the presence of aromatic substituents that also could be reduced. Furthermore, remote olefins in an isoprenoid chain survive this conjugate reduction unaffected, allowing access to isoprenoid-substituted triazole bisphosphonates of interest as potential inhibitors of terpenoid biosynthesis...
September 14, 2022: Tetrahedron Letters
https://read.qxmd.com/read/35844292/synthesis-and-anti-sars-cov-2-activity-of-deuterated-gs-441524-analogs
#17
JOURNAL ARTICLE
Wei Zheng, Tianwen Hu, Yumin Zhang, Daibao Wei, Yuanchao Xie, Jingshan Shen
The COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuing to spread around the world. GS-441524 is the parent nucleoside of remdesivir which is the first drug approved for the treatment of COVID-19, and demonstrates strong activity against SARS-Cov-2 in vitro and in vivo. Herein, we reported the synthesis of a series of deuterated GS-441524 analogs, which had deuterium atoms up to five at the ribose and the nucleobase moieties. Compared to GS-441524, all the deuterated compounds showed similar inhibitory activities against SARS-CoV-2 in vitro...
August 17, 2022: Tetrahedron Letters
https://read.qxmd.com/read/36777034/one-pot-high-throughput-synthesis-of-n-3-substituted-5-arylidene-2-thiohydantoin-amides-and-acids
#18
JOURNAL ARTICLE
Chelsi Whitely, Yangmei Li
A one-pot high-throughput solid-phase method for the synthesis of N 3-substituted 5-arylidene-2-thiohydantoin amide and acid has been developed. A tandem ring-closure and ring-open pathway is proposed as the mechanism of forming the two products.
August 3, 2022: Tetrahedron Letters
https://read.qxmd.com/read/35873104/canavanine-versus-arginine-prospects-for-cell-penetrating-peptides
#19
JOURNAL ARTICLE
Lindsey O Calabretta, Vienna M Thomas, Ronald T Raines
Octanol-water partitioning experiments in the presence of carboxylate-, phosphate-, and sulfate-containing anionic lipids revealed that Ac-Cav-NH2 (where Cav refers to δ-oxa-arginine) partitions less into octanol than does Ac-Arg-NH2 , suggesting that a cell-penetrating peptide based on canavanine would be relatively ineffective.
June 8, 2022: Tetrahedron Letters
https://read.qxmd.com/read/35846850/a-ring-expansion-approach-to-n-oxy-2-5-diketopiperazines
#20
JOURNAL ARTICLE
Amy C Jackson, James T Olsen, Sasha Sundstrom, Kyle M Lambert, John L Wood
A ring expansion of tetramic acids (pyrrolidine-2,4-diones) to N -oxy-2,5-diketopiperazines (DKPs) is described. This method allows for the facile and late-stage construction of the hydroxamic acid moiety and can thereby serve as a general method for accessing N -oxy-2,5-DKP natural products.
June 8, 2022: Tetrahedron Letters
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