5701-83-7Relevant articles and documents
1,3-Chlorine Shift to a Vinyl Cation: A Combined Experimental and Theoretical Investigation of the E-Selective Gold(I)-Catalyzed Dimerization of Chloroacetylenes
Kreuzahler, Mathis,Daniels, Alyssa,W?lper, Christoph,Haberhauer, Gebhard
, p. 1337 - 1348 (2019)
Metal-catalyzed dimerization reactions of terminal acetylenes are well known in the literature. However, only a few examples of the dimerization of halogen-substituted acetylenes are described. The products of the latter metal-catalyzed dimerization are the branched head-to-tail enynes. The formation of the corresponding linear head-to-head enynes has not been reported yet. Herein, we demonstrate by means of quantum chemical methods and experiments that the head-to-head dimerization of chloroarylacetylenes can be achieved via mono gold catalysis. Under the optimized conditions, a clean and complete conversion of the starting materials is observed and the dimeric products are obtained up to 75% NMR yield. A mechanistic investigation of the dimerization reaction reveals that the branched head-to-tail vinyl cation is energetically more stable than the corresponding linear head-to-head cation. However, the latter can rearrange by an unusual 1,3-chlorine shift, resulting in the highly stereoselective formation of the trans product, which corresponds to the gold complex of the head-to-head E-enyne. The activation barrier for this rearrangement is extremely low (ca. 2 kcal/mol). As the mono gold-catalyzed dimerization can be conducted in a preparative scale, this simple synthesis of trans-1,2-dichloroenynes makes the gold(I)-catalyzed head-to-head dimerization of chloroarylacetylenes an attractive method en route to more complex conjugated enyne systems and their congeners.
Asymmetric Synthesis of Enantiopure Pyrrolidines by C(sp3)?H Amination of Hydrocarbons
Darses, Benjamin,Dauban, Philippe,Lazib, Yanis,Retailleau, Pascal,Saget, Tanguy
, p. 21708 - 21712 (2021/08/30)
The asymmetric synthesis of enantiopure pyrrolidines is reported via a streamlined strategy relying on two sequential C?H functionalizations of simple hydrocarbons. The first step is a regio- and stereoselective catalytic nitrene C?H insertion. Then, a su
Photoredox-Catalysis-Modulated, Nickel-Catalyzed Divergent Difunctionalization of Ethylene
Li, Jiesheng,Luo, Yixin,Cheo, Han Wen,Lan, Yu,Wu, Jie
supporting information, p. 192 - 203 (2019/01/21)
Divergent synthesis that enables a catalytic reaction to selectively produce different products from common substrates will allow the charting of wider chemical space and the unveiling of distinct mechanistic paradigms. A common strategy for it employs different ligands to modulate organometallic catalysts. Dramatic developments in photocatalysis have enabled previously inaccessible transformations. In particular, photoredox catalysis modulates the oxidation state of transition-metal complexes, offering enormous opportunities for methodology development. Herein, we developed a photo-mediated divergent ethylene difunctionalization via modulating oxidation states of the nickel catalyst by using different photoredox catalysts. This work will inspire new perspectives for value-added chemical synthesis using ethylene as a feedstock and shed light on photoredox-catalyst-based divergent synthesis, which fundamentally differs from ligand-controlled transition-metal catalysis.Divergent synthesis represents a powerful strategy for directly accessing different molecular scaffolds originating from the same starting materials. Access to different end products via transition-metal catalysis is conventionally achieved by ligand control. We herein demonstrate the use of ethylene feedstock and commercially available aryl halides to accomplish the divergent synthesis of 1,2-diarylethanes, 1,4-diarylbutanes, or 2,3-diarylbutanes in a highly selective fashion through the synergistic combination of nickel and photoredox catalysis. Mechanistic studies suggest that the observed selectivity was due to different active states of Ni(I) and Ni(0) modulated by Ru- and Ir-based photoredox catalysts, respectively. The ability to access different organometallic oxidation states via photoredox catalysis promises to inspire new perspectives for synergistic transition-metal-catalyzed divergent synthesis.Functionalization of ethylene without polymerization is challenging under photo-irradiation conditions. We have demonstrated that the photo-transformation of ethylene can be controllable by merging photoredox and transition-metal catalysis. In our study, the use of different photoredox catalysts was able to modulate the oxidation state of the nickel catalyst. Through different oxidation states, the nickel-catalyzed couplings proceeded via distinct pathways to generate divergent ethylene difunctionalization products selectively from the same feedstock.
Nickel-catalyzed anti-Markovnikov hydroarylation of alkenes
Nguyen, Julia,Chong, Andrea,Lalic, Gojko
, p. 3231 - 3236 (2019/03/21)
We have developed a nickel-catalyzed hydroarylation of alkenes using aryl halides as coupling partners. Excellent anti-Markovnikov selectivity is achieved with aryl-substituted alkenes and enol ethers. We also show that hydroarylation occurs with alkyl substituted alkenes to yield linear products. Preliminary examination of the reaction mechanism suggests irreversible hydrometallation as the selectivity determining step of the hydroarylation.
Synthesis and PGE2 inhibitory activity of novel diarylheptanoids
McLane, Richard D.,Le Cozannet-Laidin, Léon,Boyle, Maxwell S.,Lanzillotta, Lindsey,Taylor, Zachary L.,Anthony, Sarah R.,Tranter, Michael,Onorato, Amber J.
supporting information, p. 334 - 338 (2018/02/15)
Prostaglandin E2 (PGE2) is a lipid mediator of inflammation and its inhibition has become a popular drug target due to its harmful physiological roles. Diarylheptanoids are one class of compounds that have shown successful inhibition of PGE2. This paper reports the synthesis and PGE2 inhibitory activity of a series of analogues of a naturally occurring diarylheptanoid. The most efficacious compounds were examined for dose-dependent PGE2 inhibition. Among several promising compounds, the lead candidate exhibited an IC50 value of 0.56 ng/μL or 1.7 μM with no detectable toxicity at the highest dose of 10 ng/μL.
Nickel-mediated inter- and intramolecular reductive cross-coupling of unactivated alkyl bromides and aryl iodides at room temperature
Yan, Chang-Song,Peng, Yu,Xu, Xiao-Bo,Wang, Ya-Wen
supporting information; experimental part, p. 6039 - 6048 (2012/06/18)
A nickel-mediated intermolecular reductive cross-coupling reaction of unactivated alkyl bromides and aryl iodides at room temperature has been developed and successfully extended to less explored intramolecular versions and tandem cyclization-intermolecular cross-coupling. Highly stereoselective (or stereospecific) synthesis of linear-fused perhydrofuro[2,3-b]furan (pyran) and spiroketal skeletons allows rapid access to these useful building blocks, which would be potentially valuable in the synthesis of relevant natural products. A rational explanation for the formation of contiguous stereogenic centers is given. Copyright
Catalytic double C-Cl bond activation in CHlby iron(III) salts with grignard reagents
Qian, Xin,Kozak, Christopher M.
experimental part, p. 852 - 856 (2011/06/21)
Cross-coupling of Grignard reagents with dichloromethane is achieved using iron(III) catalysts. Aryl- and benzylmagnesium bromides show a range of activity toward double C-Cl bond activation resulting in the insertion of methylene fragments between two equivalents of the nucleophilic partner. Georg Thieme Verlag Stuttgart.
Synthesis of 4,16-dimethoxy-1,2-dimethyl[2.4]metacyclophan-1-ene and 8,17-dimethoxy-1.2-dimethyl-10-thia[2.3.4](1,3,5)cyclophan-1-ene
Shimizu, Tomoe,Kato, Rika,Miyamoto, Shinpei,Yamato, Takehiko
body text, p. 445 - 448 (2010/12/24)
McMurry cyclisation of 1,4-bis(3-acetyl-4-methoxyphenyl)butane afforded flexible 4,16-dimethoxy-1,2-dimethyl[2.4] metacyclophan-1-ene, which was converted to the corresponding triple bridged 8,17-dimethoxy-1,2-dimethyl-10- thia[2.3.4](1,3,5)cyclophan-1-en
Di- and trivalent small molecule selectin inhibitors
-
, (2008/06/13)
The present invention provides compounds having structure (II), and the pharmaceutically acceptable salts, esters, amides and prodrugs thereof.
Novel synthetic inhibitors of selectin-mediated cell adhesion: Synthesis of 1,6-bis[3-(3-carboxymethylphenyl)-4-(2-α-D-mannopyranosyloxy)phenyl] hexane (TBC1269)
Kogan, Timothy P.,Dupré, Brian,Bui, Huong,McAbee, Kathy L.,Kassir, Jamal M.,Scott, Ian L.,Hu, Xin,Vanderslice, Peter,Beck, Pamela J.,Dixon, Richard A. F.
, p. 1099 - 1111 (2007/10/03)
Reports of a high-affinity ligand for E-selectin, sialyl di-Lewis(x) (sLe(x)Le(x), 1), motivated us to incorporate modifications to previously reported biphenyl-based inhibitors that would provide additional interactions with the protein. These compounds were assayed for the ability to inhibit the binding of sialyl Lewis(x) (sLe(x), 2) bearing HL-60 cells to E-, P-, and L- selectin fusion proteins. We report that dimeric or trimeric compounds containing multiple components of simple nonoligosaccharide selectin antagonists inhibit sLe(x)-dependent binding with significantly enhanced potency over the monomeric compound. The enhanced potency is consistent with additional binding interactions within a single selectin lectin domain; however, multivalent interaction with multiple lectin domains as a possible alternative cannot be ruled out. Compound 15e (TBC1269) showed optimal in vitro activity from this class of antagonists and is currently under development for use in the treatment of asthma.
