17601-37-5Relevant academic research and scientific papers
Aerobic Copper-Catalyzed Intramolecular Cascade Oxidative Isomerization/[4+4] Cyclization of 2,2′-Disubstituted Stilbenes
Zhang, Zhi-Jun,Zhou, Xu,Li, Dashan,Chen, Yang,Xiao, Wen-Wen,Li, Rong-Tao,Shao, Li-Dong
supporting information, p. 7609 - 7624 (2021/05/29)
An aerobic copper-catalyzed cascade oxidative isomerization/[4+4] cyclization of 2,2′-disubstituted stilbenes is described. Under the mild CuCl/DBED/air catalytic system, various 5,10-heteroatom-containing tetrahydroindeno[2,1-a]indenes were efficiently p
E, Z -Selectivity in the reductive cross-coupling of two benzaldehydes to stilbenes under substrate control
Arkhypchuk, Anna I.,D'Imperio, Nicolas,Ott, Sascha
, p. 6171 - 6179 (2020/10/21)
Unsymmetrical E- and Z-stilbenes can be synthesized from two differently substituted benzaldehydes in a MesP(TMS)Li-promoted reductive coupling sequence. Depending on the order of addition of the two coupling partners, the same olefin can be produced in either E- or Z-enriched form under identical reaction conditions. A systematic study of the correlation between the stereochemical outcome of the reaction and the substitution pattern at the two aldehydes is presented. The results can be used as guidelines to predict the product stereochemistry. This journal is
A Bisphenolic Honokiol Analog Outcompetes Oral Antimicrobial Agent Cetylpyridinium Chloride via a Membrane-Associated Mechanism
Ochoa, Cristian,Solinski, Amy E.,Nowlan, Marcus,Dekarske, Madeline M.,Wuest, William M.,Kozlowski, Marisa C.
, p. 74 - 79 (2019/11/20)
Targeting Streptococcus mutans is the primary focus in reducing dental caries, one of the most common maladies in the world. Previously, our groups discovered a potent bactericidal biaryl compound that was inspired by the natural product honokiol. Herein, a structure activity relationship (SAR) study to ascertain structural motifs key to inhibition is outlined. Furthermore, mechanism studies show that bacterial membrane disruption is central to the bacterial growth inhibition. During this process, it was discovered that analog C2 demonstrated a 4-fold better therapeutic index compared to the commercially available antimicrobial cetylpyridinium chloride (CPC) making it a viable alternative for oral care.
Photoinitiated carbonyl-metathesis: Deoxygenative reductive olefination of aromatic aldehydes: Via photoredox catalysis
Wang, Shun,Lokesh, Nanjundappa,Hioe, Johnny,Gschwind, Ruth M.,K?nig, Burkhard
, p. 4580 - 4587 (2019/05/14)
Carbonyl-carbonyl olefination, known as McMurry reaction, represents a powerful strategy for the construction of olefins. However, catalytic variants that directly couple two carbonyl groups in a single reaction are less explored. Here, we report a photoredox-catalysis that uses B2pin2 as terminal reductant and oxygen trap allowing for deoxygenative olefination of aromatic aldehydes under mild conditions. This strategy provides access to a diverse range of symmetrical and unsymmetrical alkenes with moderate to high yield (up to 83%) and functional-group tolerance. To follow the reaction pathway, a series of experiments were conducted including radical inhibition, deuterium labelling, fluorescence quenching and cyclic voltammetry. Furthermore, NMR studies and DFT calculations were combined to detect and analyze three active intermediates: a cyclic three-membered anionic species, an α-oxyboryl carbanion and a 1,1-benzyldiboronate ester. Based on these results, we propose a mechanism for the CC bond generation involving a sequential radical borylation, "bora-Brook" rearrangement, B2pin2-mediated deoxygenation and a boron-Wittig process.
A Novel Catalyst-Free Synthesis of 2,2-Diaryl Enamides from Stilbenes via a Nitrene Transfer Reaction
Zhang, Yuanyuan,Ye, Wenjing,Zhang, Hui,Xiao, Xiao
supporting information, p. 5720 - 5724 (2019/08/26)
A novel catalyst-free nitrene transfer reaction between stilbenes and iminoiodinanes was achieved for the first time, which provides an efficient and environmentally friendly way to access variously substituted 2,2-diaryl enamides under mild conditions. Mechanistic investigations suggested the reaction proceed via nitrene transfer and aromatic rearrangement with iminoiodinane also acting as a Lewis acid, benefitting the ring-opening of the aziridine intermediate.
E-Stilbene derivatives synthesized by stereoselective reductive coupling of benzylic gem-dibromide promoted by Cu/polyamine
Cao, Hua,Wang, Qi
, p. 2703 - 2706 (2017/06/23)
Stereoselective reductive coupling reaction of benzylic gem-dibromide promoted by Cu/polyamine produces E-stilbene derivatives with high yield under mild conditions. It provides a short pathway to synthesize symmetrical and asymmetrical E-stilbene derivatives using cheap reagents and alkenyl-free starting material together with easy workup.
Phenanthrene Synthesis via Chromium-Catalyzed Annulation of 2-Biaryl Grignard Reagents and Alkynes
Yan, Jianming,Yoshikai, Naohiko
supporting information, p. 6630 - 6633 (2017/12/26)
A chromium/2,2′-bipyridine-catalyzed annulation reaction of 2-biarylmagnesium reagents with alkynes is reported. The reaction is applicable to a variety of aryl- and/or alkyl-substituted internal alkynes as well as 2-biaryl and related Grignard reagents, thus affording phenanthrene derivatives in moderate to good yields. The reaction proceeds at the expense of excess alkyne as a hydrogen acceptor and thus does not need an external oxidant. Deuterium-labeling experiments shed light on the reaction mechanism, which likely involves multiple intramolecular C-H activation processes on chromium.
Immobilization and continuous recycling of photoredox catalysts in ionic liquids for applications in batch reactions and flow systems: Catalytic alkene isomerization by using visible light
Fabry, David C.,Ronge, Meria A.,Rueping, Magnus
supporting information, p. 5350 - 5354 (2015/03/30)
A catalytic (E)- to (Z)-isomerization of olefins using a photoredox catalyst under mild reaction conditions is presented. A variety of (Z)-alkenes can be prepared in the presence of visible light. A new reaction system allows an easy and efficient scale-up, as well as a continuous flow process in which the photocatalyst is immobilized in an ionic liquid and continuously recycled by simple phase separation. Catalytic (E)- to (Z)-isomerizations of olefins under mild conditions can be achieved by use of a photosensitizer and visible light. A new reaction system such as depicted allows an easy and efficient scale-up, as well as continuous flow processes in which the photocatalyst is immobilized in an ionic liquid and continuously recycled by phase separation.
Synthesis of combretastatin A-4 O-alkyl derivatives and evaluation of their cytotoxic, antiangiogenic and antitelomerase activity Dedicated to Professor G. Asensio, University of Valencia, on the occasion of his 65th birthday
Torijano-Gutiérrez, Sandra,Díaz-Oltra, Santiago,Falomir, Eva,Murga, Juan,Carda, Miguel,Marco, J. Alberto
, p. 7267 - 7274 (2013/11/19)
We here report the synthesis and biological evaluation of several combretastatin A-4 derivatives alkylated at the phenol hydroxyl group. Some of these derivatives contain an (E)-arylalkene fragment reminiscent of that present in some natural stilbenes like resveratrol. The cytotoxicities towards one human healthy kidney embryonic and two tumoral cell lines were determined. In addition, the ability of these compounds to inhibit the production of the vascular endothelial growth factor (VEGF) was measured. Finally, the expression of genes controlling the production of telomerase was measured. Some of the compounds were found to have an activity comparable or higher than that of combretastatin A-4 in at least one of the aforementioned biological properties. The compounds with the (E)-arylalkene fragment were in general terms more active than the simple O-alkyl derivatives. However, no clear structure/activity correlations were perceived when comparing the observed compound activities across the three biological properties. This points out the existence of marked differences between the mechanisms responsible for their cytotoxicity.
Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
Byrne, Peter A.,Gilheany, Declan G.
supporting information; experimental part, p. 9225 - 9239 (2012/07/14)
The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
