619-93-2Relevant academic research and scientific papers
Second-generation aryl isonitrile compounds targeting multidrug-resistant Staphylococcus aureus
Kyei-Baffour, Kwaku,Mohammad, Haroon,Seleem, Mohamed N.,Dai, Mingji
, p. 1845 - 1854 (2019/03/28)
Antibiotic resistance remains a major global public health threat that requires sustained discovery of novel antibacterial agents with unexploited scaffolds. Structure-activity relationship of the first-generation aryl isonitrile compounds we synthesized led to an initial lead molecule that informed the synthesis of a second-generation of aryl isonitriles. From this new series of 20 compounds, three analogues inhibited growth of methicillin-resistant Staphylococcus aureus (MRSA) (from 1 to 4 μM) and were safe to human keratinocytes. Compound 19, with an additional isonitrile group exhibited improved activity against MRSA compared to the first-generation lead compound. This compound emerged as a candidate worthy of further investigation and further reinforced the importance of the isonitrile functionality in the compounds’ anti-MRSA activity. In a murine skin wound model, 19 significantly reduced the burden of MRSA, similar to the antibiotic fusidic acid. In summary, 19 was identified as a new lead aryl isonitrile compound effective against MRSA.
Supported palladium nanoparticles as heterogeneous ligand-free catalysts for the Hiyama C-C coupling of vinylsilanes and halobenzenes leading to styrenes
Grirrane, Abdessamad,Garcia, Hermenegildo,Corma, Avelino
, p. 49 - 57 (2013/06/27)
The Hiyama C-C coupling reaction of a wide range of aryl iodides and vinylsilanes has been performed using ligand-free solid catalysts based on supported palladium nanoparticles. Among the supports tested (Mg, TiO 2, CeO2 and active carbon), the most active catalysts were those in which palladium is supported on MgO and TiO2. Analogous Pt and Au materials were inefficient to promote this reaction. Leaching tests suggest that there is some contribution of dissolved Pd since Pd in solution has been detected and the scavenging test decreases the initial reaction rate. Although the solid Pd catalysts can be reused, it was, however, observed that they undergo a certain deactivation upon use that can be attributed to several factors including the presence of inorganic compounds on the catalyst, Pd leaching or agglomeration of Pd NPs.
Olefin cross-metathesis/Suzuki-Miyaura reactions on vinylphenylboronic acid pinacol esters
Baltus, Christine B.,Chuckowree, Irina S.,Press, Neil J.,Day, Iain J.,Coles, Simon J.,Tizzard, Graham J.,Spencer, John
supporting information, p. 1211 - 1217 (2013/03/13)
A series of alkenyl phenylboronic acid pinacol esters has been synthesized via an olefin cross-metathesis reaction of vinylphenylboronic acid pinacol ester derivatives. After catalytic hydrogenation, the resulting boronates were coupled via a microwave-mediated Suzuki-Miyaura reaction to afford a library of biarylethyl aryl and biarylethyl cycloalkyl derivatives. A complementary reaction sequence involved an initial Suzuki-Miyaura coupling.
Dehydrogenation of nitro derivatives of bibenzyl to corresponding nitro stilbene with dioxygen catalyzed by 2,2,6,6-tetramethylpiperidine-1-oxyl
Lu, Tingting,Lu, Ming
, p. 971 - 975 (2013/02/25)
A simple and effective oxidative dehydrogenation of nitro derivatives of bibenzyl was developed using a mixture of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and metal salts as catalyst under an atmospheric pressure of oxygen. The oxidation of several nitro derivatives of bibenzyl led to corresponding nitro stilbene in good yields, and the yields increased with the increase in the substituted nitro group on the bibenzyl. For example, the aerobic dehydrogenation of 2,2,4,4,6,6-hexanitrobibenzyl in the presence of a catalytic amount of TEMPO with metal salts gave 2,2,4,4,6,6-hexanitrostilbene in 81 % yield and 4,4-dinitrostilbene-2,2-disulfonic acid (75 %) was obtained from 4,4-dinitrobibenzyl-2,2-disulfonic acid. Iranian Chemical Society 2012.
Synthesis of stilbene analogues by one-pot oxidation-Wittig and oxidation-Wittig-Heck reaction
Saiyed, Akeel S.,Patel, Krupa N.,Kamath, Bola V.,Bedekar, Ashutosh V.
supporting information; experimental part, p. 4692 - 4696 (2012/09/10)
Synthesis of symmetrical (and unsymmetrical) stilbene derivatives is achieved by a combination of one-pot steps of Kornblum type oxidation of benzyl halide, its simultaneous in situ formation of phosphonium salt, and subsequently their Wittig reaction. In other variant it is oxidized to aldehyde, treated with ylide generated from phosphonium salt (CH3PPh3X) to give styrene, and subjected to Pd catalyzed Heck reaction with arylhalide to give stilbenes as the three-step one-pot sequence.
On the dual role of N-heterocyclic carbenes as bases and nucleophiles in reactions with organic halides
Knappke, Christiane E. I.,Arduengo, Anthony J.,Jiao, Haijun,Neudoerfl, Joerg-Martin,Jacobivonwangelin, Axel
scheme or table, p. 3784 - 3795 (2012/01/11)
The synthetic consequences of different basicities, nucleophilicities, and sterics of N-heterocyclic carbenes have been studied in reactions of imidazolin-2-ylidenes with organic halides. Highly nucleophilic and less basic carbenes cleanly gave alkyli-deneimidazolines, the deoxy analogues of Breslow-type intermediates. More basic NHCs engaged in unwanted deprotonation or dehydrohalogenation reactions. Georg Thieme Verlag Stuttgart. New York.
Gelation ability of novel oxamide-based derivatives bearing a stilbene as a photo-responsive unit
Miljanic, Snezana,Frkanec, Leo,Meic, Zlatko,Zinic, Mladen
, p. 1323 - 1334 (2007/10/03)
Oxamide-based derivatives containing one or two oxamide moieties coupled to the 4- or 4,4′-positions of cis- and transstilbene have been synthesised. In order to modulate the solvent gelation tendencies, a series of derivatives with modified terminal functions were prepared from them. The transstilbene dioxamide-based derivatives were found to be sparingly soluble or insoluble in water and in organic solvents, whereas the trans-stilbene monooxamide-based derivatives are soluble in most organic solvents. Incorporation of a C 12 alkyl chain in the structure of the latter compounds results in a decreased solubility but in an increased gelation tendency of the substances. The ethyl ester oxamide-based derivative trans-3a and the amino acid oxamide-based derivative trans-3e act as efficient gelators of various organic solvents. In contrast, cis-3a shows a poor gelation ability or none at all, owing to its good solubility. Considering the difference in gelation abilities of the compounds trans-3a and cis-3a and the photo-responsive conformational changes of the stilbene part of the molecule, a controlled gelation by light was achieved. FT-IR and 1H NMR spectroscopic measurements support the view that hydrogen bonding between the oxamide fragments plays an important role in gel formation. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
3,5-Bis(trifluoromethyl)phenyl sulfones in the direct Julia-Kocienski olefination
Alonso, Diego A.,Fuensanta, Monica,Najera, Carmen,Varea, Montserrat
, p. 6404 - 6416 (2007/10/03)
3,5-Bis(trifluoromethyl)phenyl (BTFP) sulfones 7 have been employed in the Julia-Kocienski olefination reaction with carbonyl compounds. Sulfones 7 are readily prepared in high yields (64-97%) from commercially available 3,5-bis(trifluoromethyl)thiophenol through an alkylation/oxidation two-step sequence. The stability of metalated BTFP sulfones has been studied and compared with heteroaryl benzothiazol-2-yl (BT), 1-phenyl-1H-tetrazol-5-yl (PT), and 1-tert-butyl-1H-tetrazol-5-yl (TBT) sulfones 9-11 under different reaction conditions. The Julia-Kocienski olefination between alkyl BTFP sulfones 7 and a wide variety of aldehydes affords the corresponding 1,2-disubstituted alkenes and dienes in good yields and stereoselectivities. This one-pot protocol can be performed using KOH at room temperature or the phosphazene bases P2-Et and P4-t-Bu at -78 °C or rt and has been successfully used in a high-yielding and stereoselective synthesis of various methoxylated stilbenes such as trimethylated resveratrol. These new reaction conditions for the Julia-Kocienski olefination reaction have been also studied with BT, PT, and TBT sulfones, giving poorer results. Methylenation of aliphatic and aromatic aldehydes, ketones, and 1,2-dicarbonyl compounds is carried out through the modified Julia olefination using BTFP methyl sulfone 7d to give terminal alkenes and dienes. Mechanistic studies of the olefination reaction between benzyl BTFP sulfone 7a and aromatic aldehydes performed by KOH-induced Smiles rearrangement of stereodefined syn- and anit-β-hydroxyalkyl BTFP sulfones indicate that the stereocontrol of the reaction is determined in the elimination step. 2005 American Chemical Society.
Aqueous Wittig reactions of aldehydes with in situ formed semistabilized phosphorus ylides
Wu, Jinlong,Zhang, Da
, p. 2543 - 2551 (2007/10/03)
The Wittig reactions of three semistabilized phosphorus ylides generated in situ from the corresponding phosphonium salts with aldehydes in water without any organic cosolvent were investigated. Most of the olefination reactions completed within between 5 min and 4.5 h in refluxing water containing 1.5 equiv of LiOH and 1.4M LiCl to afford the products in 65-100% yields. The E:Z selectivity depended not only on the substituent attached to the benzene ring of the ylides but also on the substituent bound to the aromatic aldehydes. LiCl promotes the aqueous Wittig reactions and suppresses decomposition of the ylide or the corresponding phosphonium salt. Copyright Taylor & Francis, Inc.
Experimental evidence for multiple oxidation pathways in the (salen)Mn-catalyzed epoxidation of alkenes
Linde, Christian,Koliai, Nordine,Norrby, Per-Ola,Akermark, Bjoern
, p. 2568 - 2573 (2007/10/03)
The substrate electronic effects on the selectivity in the catalytic epoxidation of para-substituted cis stilbenes 2a-i were investigated by using (R,R)-[N,N′-bis(3,5-di-tBu-salicylidene)-1,2-cyclohexanediamine] manganese(III) chloride 1 in benzene as the catalyst with iodosobenzene as the terminal oxidant. A Hammett study of the selectivity results reveals a stronger electrophilic character than previously assumed in the (salen)Mn-catalyzed reaction. In general, the best correlations with the experimental values were obtained by using the Hammett σ+ values, which gave ρ = -1.37 for the rate of cisepoxide formation and ρ = -0.43 for the rate of the stepwise process leading to the corresponding trans product. The reaction involves two separate pathways as indicated also by the competitive breakdown of the intermediate on the path to trans epoxide for methoxy-substituted substrates. The asynchronicity in the concerted pathway leading to cis epoxide is apparent for 4-methoxy-4′-nitrostilbene, which yields cis epoxide with 75% ee entirely as a result of electronic effects.
