186581-53-3Relevant articles and documents
Synthesis of cyclopropanated [2.2.1] heterobicycloalkenes: An improved procedure
Carlson, Emily,Duret, Guillaume,Blanchard, Nicolas,Tam, William
, p. 55 - 62 (2016)
A safer and improved method to our previous report on palladium-catalyzed cyclopropanation of heterobicyclic alkenes has been developed. By using tetrahydrofuran as the solvent and a more dilute aqueous NaOH solution for the generation of diazomethane fro
BACKBONE REARRANGEMENTS OF METHYL (-)-KAUR-9(11)-EN-19-OATE AND ITS EPOXIDE: STRUCTURES OF TWO DITERPENES OF A NEW SKELETAL TYPE
Nakano, Tatsuhiko,Spinelli, A. C.,Martin, A.,Usubillaga, A.,McPhail, Andrew P.,Onan, Kay D.
, p. 3627 - 3630 (1982)
Cleavage of the epoxide (2) of methyl (-)-kaur-9(11)-en-19-oate (1b) with boron trifluoride-ether in benzene and in acetic anhydride yielded (3a) and (3b), respectively.On epoxidation with m-chloroperbenzoic acid in the presence of N-nitrosomethyl urea, (1b) suffered a backbone rearrangement to form (6).
A carbonyl ylide cycloaddition approach to platensimycin
Kim, Chan Hyuk,Jang, Ki Po,Choi, Soo Young,Chung, Young Keun,Lee, Eun
, p. 4009 - 4011 (2008)
(Chemical Presented) Short and to the point: A formal synthesis of platensimycin has been accomplished by employing a carbonyl ylide [3+2] cycloaddition reaction (see scheme). This short and facile enantioselective synthesis of the pivotal tetracyclic precursor requires 11 steps and proceeds in 20% overall yield from isopropyl cyanoacetate.
Concise synthesis of alkaloid (-)-205B
Rao, Nagavaram Narsimha,Cha, Jin Kun
, p. 2243 - 2246 (2015)
Described herein is a short total synthesis of alkaloid (-)-205B (1) by means of an anti-selective SN2 alkylation of an attractively functionalized cyclopropanol and diastereoselective cyclization of the resulting aminoallene adduct for bicyclic ring formation. The synthesis features a general route to cis- or trans-2,6-disubstituted piperidines by lithium aluminum hydride reduction of the imine intermediate by an appropriate choice of solvent and cis- or trans-2,5-disubstituted pyrrolidines by an exceptional level of chirality transfer from a pendant allene. Particularly noteworthy are the brevity and convergence made possible by a segment-coupling strategy.
An enantiospecific synthesis of a komarovispirane
Srikrishna, Adusumilli,Beeraiah
, p. 2587 - 2597 (2007)
The enantiospecific total synthesis of a komarovispirane, containing the complete carbon framework, trans-bicyclo[4.3.0]nonanespiro[8.1′]cyclohexane, of the spiroditerpene komarovispirone, starting from the readily available campholenaldehyde is described
Isolation and structural identification of a direct-acting mutagen derived from N-nitroso-N-methylpentylamine and Fenton's reagent with copper ion
Miura, Motofumi,Inami, Keiko,Yoshida, Masafumi,Yamaguchi, Kentaro,Mashino, Tadahiko,Mochizuki, Masataka
, p. 5693 - 5697 (2011)
N-Nitrosodialkylamines show their mutagenicity by forming α-hydroxynitrosamines in the presence of rat S9 mix in the Ames assay. The hydroxyl radical derived from Fe2+-H2O2 (Fenton's reagent) with Cu2+ activates N-nitrosamines, with an alkyl chain longer than a propyl constituent, to a direct-acting mutagen. The reactivity of Fe2+-Cu2+-H2O2 on nitrosamines in relation to their metabolic activation is not fully characterized. Here, we report the identification of the direct-acting mutagen derived from N-nitroso-N-methylpentylamine (NMPe) in the presence of Fe 2+, Cu2+, H2O2 and nitric oxide (NO), which is a product of nitrosamine metabolism. A dichloromethane extract of the NMPe reaction mixtures was fractionated by silica gel column chromatography several times and by a preparative high performance liquid chromatography (HPLC); we obtained white crystals as a product. The direct-acting mutagen that was isolated was provisionally identified as 5-ethyl-5-nitro-1-pyrazoline 1-oxide by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and X-ray crystallography. To confirm the structure of the mutagen, the authentic compound was synthesized from 2-nitrobutene and diazomethane, followed by N-oxidation with m-chloroperoxybenzoic acid. The 1H NMR spectral data from the direct-acting mutagen that was synthesized was identical to the data from the isolated mutagen. Furthermore, the authentic 5-ethyl-5-nitro-1-pyrazoline 1-oxide was mutagenic in Salmonella typhimurium TA1535. The results showed that 5-ethyl-5-nitro-1-pyrazoline 1-oxide was a direct-acting mutagen derived from the reaction of NMPe and Fe2+-Cu2+-H2O 2-NO.
Carbenoid insertion into the peroxide bond vs the olefin bond of cyclic peroxides
Zvarec, Ondrej,Avery, Thomas D.,Taylor, Dennis K.
, p. 450 - 454 (2010)
(Chemical Equation Presented) Herein we report examples of the insertion of a carbenoid into a peroxide linkage. This study reveals that intramolecular insertion of carbenes into the peroxide linkage of 3,6-dihydro-1,2-dioxines is preferred over olefin insertion. The initial scope of the reaction and mechanistic considerations, have been probed. This methodology also generates unusual bicyclic hemiacetals (2) and tricyclic peroxides (3).
Vibrational Energy Distributions of Singlet Methylene from Photolyses Ketene, Ketene-d2, Diazomethane, and Diazomethane-d2 at Several Wavelengths. A Chemically Activated Methylcyclobutene Study
Mahone, W. C.,Kolln, W.,Simons, J. W.
, p. 3902 - 3907 (1985)
The energy distributions of singlet methylene upon reaction with cyclobutane have been determined for methylene from photolysis of ketene and ketene-d2 at 214 nm, diazomethane at 436, 366, 337, 229 nm, and diazomethane-d2 at 366 nm.Earlier results for diazomethane photolyses at 436 and 366 nm are extended and reanalyzed in terms of a more recent stepsize determination for collosional deactivation of chemically activated methylcyclobutane.The widths of the singlet methylene energy distributions were found to increase with increasing photon energy and with deuterium substitution.An extensive analysis in terms of a statistical energy partitioning model for photodissociation of ketene and diazomethane is given and discussed.
Antiparasitic activity of natural and semi-synthetic tirucallane triterpenoids from Schinus terebinthifolius (anacardiaceae): Structure/activity relationships
Morais, Thiago R.,Da Costa-Silva, Thais A.,Tempone, Andre G.,Borborema, Samanta Etel T.,Scotti, Marcus T.,De Sousa, Raquel Maria F.,Araujo, Ana Carolina C.,De Oliveira, Alberto,De Morais, Sergio Antonio L.,Sartorelli, Patricia,Lago, Joao Henrique G.
, p. 5761 - 5776 (2014)
Leishmaniasis and Chagas are diseases caused by parasitic protozoans that affect the poorest population in the World, causing a high mortality and morbidity. As a result of highly toxic and long-term treatments, the discovery of novel, safe and more efficacious drugs is essential. In this work, the in vitro antiparasitic activity and mammalian cytotoxicity of three natural tirucallane triterpenoids, isolated from leaves of Schinus terebinthifolius (Anacardiaceae), and nine semi-synthetic derivatives were investigated against Leishmania (L.) infantum and Trypanosoma cruzi. Trypomastigotes of T. cruzi were the most susceptible parasites and seven compounds demonstrated a trypanocidal activity with IC50 values in the range between 15 and 58 μg/mL. Four compounds demonstrated selectivity towards the intracellular amastigotes of Leishmania, with IC50 values in the range between 28 and 97 μg/mL. The complete characterization of triterpenoids was afforded after thorough analysis of nuclear magnetic resonance (NMR) data as well as electrospray ionization mass spectrometry (ESI-MS). Additionally, structure-activity relationships were performed using Decision Trees.
Synthesis of carbazole analogs via Grob fragmentation of norbornyl α-diketones
Sravanthi, Kadavergu,Agrawal, Sumit Kumar,Rao, Chintada Nageswara,Khan, Faiz Ahmed
, p. 3449 - 3452 (2016)
A regioselective synthesis of carbazole analogs belonging to both the categories of natural origin, viz., microorganisms and higher plant source is reported. The synthesis of carbazole derivatives possessing a methylester group at C-1 position has been ac
Design and synthesis of novel xyloketal derivatives and their vasorelaxing activities in rat thoracic aorta and angiogenic activities in zebrafish angiogenesis screen
Xu, Zhongliang,Li, Yiying,Xiang, Qi,Pei, Zhong,Liu, Xilin,Lu, Bingtai,Chen, Ling,Wang, Guanlei,Pang, Jiyan,Lin, Yongcheng
, p. 4642 - 4653 (2010)
A novel series of xyloketal derivatives (1-21) were designed and prepared. The majority of the compounds demonstrated vasorelaxation action on 60 mM KCl-induced contractions rat isolated aortic rings in a concentration-dependent manner, and the action is mediated by both endothelium-independent and endothelium-dependent mechanisms. Compounds 9, 12, 13, 14, 15, and 19 showed higher vasorelaxation activities comparing with the lead compound 3. In addition, these derivatives had potential protective action against oxLDL-induced endothelial oxidative injury and enhanced NO production in HUVECs without toxic effects. The NO release was completely inhibited by eNOS inhibitor L-NAME. Furthermore, 3 significantly promoted the angiogenesis in zebrafish in a concentration-dependent manner at 0.1, 1, and 10 μM. Compounds 9, 12, 14, 16, 20, and 21 exhibited stronger angiogenic activities than 3. Therefore, xyloketal derivatives are unique compounds with multiple pharmacological properties and may have potential implications in the treatment of cardiovascular diseases.
Syntheses of spiroindole melatonin analogues via 2-(indolin-3-ylidene)acetonitrile cycloadditions
Lozinskaya, Natalia A.,Volkova, Maria S.,Seliverstov, Michael Yu.,Temnov, Victor V.,Sosonyuk, Sergey E.,Proskurnina, Marina V.,Zefirov, Nikolai S.
, p. 260 - 261 (2014)
2-(2-Oxo-1,2-dihydro-3H-indol-3-ylidene)acetonitriles were subjected to cycloaddition reactions at the double bond affording spiroindole melatonin analogues.
Stereospecific mono- and difluorination of the C7-bridge of norbornenes
Rajsfus, David E.,Alter-Zilberfarb, Sari,Sharon, Pessia,Meador, Mary Ann B.,Frimer, Aryeh A.
, p. 339 - 347 (2011)
Fluorinated norbornenes are very desirable monomers in the semiconductor and high-temperature polyimide industries. We describe herein a synthetic strategy for the stereospecific mono- or difluorination of the C 7-carbon in norbornene systems beginning with 7-ketonadic anhydride 1. In particular, anti-7-fluoro methyl diester 4 and its 7,7-difluoronadic analog 7 can be prepared from 1 in 3 or 4 steps: saponification, reduction (for 4), esterification, fluorination with DAST. In addition, anti-7-fluoro-syn-7- fluoromethylnadic diester 16 is obtained from epoxide 14, and dimethyl 7,7-difluorobicyclo[2.2.2]oct-5-ene-2,3-dicarboxylate (17) from ketone 15. Anchimeric assistance of the norbornene double bond guides the introduction of attacking fluoride anions stereospecifically anti to the olefinic linkage.
Perfluoro-tert-butyl-homoserine as a sensitive 19F NMR reporter for peptide-membrane interactions in solution
Buer, Benjamin C.,Levin, Benjamin J.,Marsh, E. Neil G.
, p. 308 - 314 (2013)
Fluorine (19F) NMR is a valuable tool for studying dynamic biological processes. However, increasing the sensitivity of fluorinated reporter molecules is a key to reducing acquisition times and accessing transient biological interactions. Here,
Synthesis of halo-substituted framework derivatives of quinopimaric acid
Vafina,Uzbekov,Galin,Yunusov
, p. 1035 - 1038 (2014)
6-Chloro-, 6-chloroacetoxy-, and 16-(2-bromoacetyl)framework derivatives were synthesized from a photoadduct of quinopimaric acid.
Synthetic studies on strictamine: Unexpected oxidation of tertiary amine in Ru-catalyzed ring-closing olefin metathesis
Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
, p. 377 - 380 (2013)
During synthetic studies toward strictamine, unexpected oxidation of tertiary amine to enamine was observed in ring-closing olefin metathesis (RCM) using Hoveyda-Grubbs 2nd catalyst. Control experiments under deoxygenated conditions indicated Ru-catalyst
PROTONATION OF DIAZOMETHANE IN SUPERACID MEDIA.
McGarrity,Cox,Phillip
, p. 3961 - 3966 (1983)
Protonation on both terminals of diazomethane can be observed only under conditions of kinetic control in extremely acidic solutions, when the acidity is reduced only the thermodynamically more stable C-protonated isomer can be seen. Loss of nitrogen from the methanediazonium ion is nucleophile assisted in the very highly acidic medium of HOSO//2F/SbF//5/SO//2ClF.
A simple method of synthesis of 3-carboxy-2,2,5,5-tetraethylpyrrolidine-1-oxyl and preparation of reduction-resistant spin labels and probes of pyrrolidine series
Dobrynin, Sergey A.,Usatov, Mikhail S.,Zhurko, Irina F.,Morozov, Denis A.,Polienko, Yuliya F.,Glazachev, Yurii I.,Parkhomenko, Dmitriy A.,Tyumentsev, Mikhail A.,Gatilov, Yuri V.,Chernyak, Elena I.,Bagryanskaya, Elena G.,Kirilyuk, Igor A.
, (2021/09/28)
Stable free radicals are widely used as molecular probes and labels in various biophysical and biomedical research applications of magnetic resonance spectroscopy and imaging. Among these radicals, sterically shielded nitroxides of pyrrolidine series demonstrate the highest stability in biological systems. Here, we suggest new convenient procedure for preparation of 3-carboxy-2,2,5,5-tetraethylpyrrolidine-1-oxyl, a reduction-resistant analog of widely used carboxy-Proxyl, from cheap commercially available reagents with the yield exceeding the most optimistic literature data. Several new spin labels and probes of 2,2,5,5-tetraethylpyrrolidine-1-oxyl series were prepared and reduction of these radicals in ascorbate solutions, mice blood and tissue homogenates was studied.
The reagent Et2AlX/CH2N2 in cyclopropanation of sterically hindered olefins, as well as oxygen- and nitrogen-containing unsaturated compounds
Ramazanov,Yaroslavova,Yaubasarov,Gil’manova,Dzhemilev
, p. 1869 - 1873 (2019/10/22)
A transition-metal-free method of cyclopropanation of sterically hindered olefins, substituted allylic alcohols, allylamines, and vinyl silyl ethers was developed using diazomethane in the presence of organic aluminum halides.
