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71.
Sulfonium Ylides by (3+2) Cycloaddition of Arynes with Vinyl Sulfides: Stereoselective Synthesis of Highly Substituted Alkenes
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Yuanming Li Dr. Christian Mück‐Lichtenfeld Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2016,55(46):14435-14438
The reaction of in situ generated arynes with vinyl sulfides provides benzannulated sulfonium ylides in a (3+2) cycloaddition. Trapping of the intermediate ylides with electrophiles (proton transfer or a second aryne addition) and subsequent β‐elimination give rise to di‐, tri‐, or tetrasubstituted alkenes with high stereoselectivity. Experimental studies and DFT calculations provide insight into the mechanisms of these cascade reactions. 相似文献
72.
Yuan-Ze Xu Dr. Feng Sha Prof. Dr. Xin-Yan Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):1066-1071
The 2,2-dimethyl-2H-chromene motif is widely found in many bioactive molecules, and is a privileged structure in the pharmaceutical arena. We have developed a concise and regioselective approach to chromenes and chromanes through an aryne-based synthetic strategy. A practical, gram-scale synthetic route to a chromene-type aryne precursor was explored. Subsequently, cyclization under mild conditions afforded tetracyclic xanthone skeletons with excellent regioselectivity. Our approach provides a concise strategy for the gram-scale synthesis of chromene-type xanthones such as 6-deoxyisojacareubin, cylindroxanthone D, staudtiixanthone D, brasilixanthone A and cudracuspixanthone O. 相似文献
73.
Linear Optical and Third‐Order Nonlinear Optical Properties of Some Fluorenyl‐ and Triarylamine‐Containing Tetracyanobutadiene Derivatives
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Ziemowit Pokladek Dr. Nicolas Ripoche Dr. Marie Betou Dr. Yann Trolez Dr. Olivier Mongin Dr. Joanna Olesiak‐Banska Dr. Katarzyna Matczyszyn Prof. Marek Samoc Prof. Mark G. Humphrey Dr. Mireille Blanchard‐Desce Dr. Frédéric Paul 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10155-10167
The synthesis and characterization of four new tetracyanobutadiene (TCBD) derivatives ( 1 – 3 and 2′ ) incorporating 2‐ or 2,7‐fluorenyl and diphenylamino moieties are reported. The electroactivity of 1–3 and 2′ was studied by cyclic voltammetry (CV), while the linear optical and (third‐order) nonlinear optical (NLO) properties were investigated by electronic spectroscopy and Z‐scan studies, respectively. All experimental investigations were rationalized by DFT computations, providing an insight into the electronic structure of these derivatives and on their application potential. We show that these derivatives are nonluminescent in solution at ambient temperatures, but become fluorescent in solvent glasses. This finding constitutes an unprecedented observation for TCBD derivatives. Also, we show by Z‐scan studies that these derivatives behave as two‐photon absorbers in the near‐IR range (800–1050 nm). These third‐order NLO properties are discussed and compared with those of their alkynyl precursors ( 4 – 6 ), which have been investigated by two‐photon excited fluorescence (TPEF). 相似文献
74.
Bruno Schuler Sara Collazos Dr. Leo Gross Dr. Gerhard Meyer Dr. Dolores Pérez Prof. Dr. Enrique Guitián Dr. Diego Peña 《Angewandte Chemie (International ed. in English)》2014,53(34):9004-9006
The successful synthesis of a threefold symmetric C78H36 molecule with 22 fused benzene rings is reported. This clover‐shaped nanographene was characterized on an ultrathin insulating film with atomic resolution by scanning probe microscopy. 相似文献
75.
Subrata Bhattacharjee Anjali Raju Rahul N. Gaykar Rajesh G. Gonnade Tony Roy Akkattu T. Biju 《化学:亚洲杂志》2020,15(14):2203-2207
A mild and easy to perform multicomponent coupling involving phosphines, arynes generated from 2‐(trimethylsilyl)aryl triflates, and CO2 allowing the transition‐metal‐free synthesis of zwitterionic phosphonium benzoates has been developed. The reaction proceeds via the generation of 1 : 1 zwitterionic intermediates from phosphines and arynes followed by the interception with CO2 to deliver the carboxylates in moderate to good yields instead of the anticipated benzooxaphosphol‐3(1H)‐ones. 相似文献
76.
Longji Li Dr. Yao Li Prof. Dr. Niankai Fu Prof. Dr. Long Zhang Prof. Dr. Sanzhong Luo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(34):14453-14457
Asymmetric catalysis with benzyne remains elusive because of the highly fleeting and nonpolar nature of benzyne intermediates. Reported herein is an electrochemical approach for the oxidative generation of benzynes (cyclohexyne) and its successful merging with chiral primary aminocatalysis, formulating the first catalytic asymmetric enamine–benzyne (cyclohexyne) coupling reaction. Cobalt acetate was identified to stabilize the in situ generated arynes and facilitate its coupling with an enamine. This catalytic enamine-benzyne protocol provides a concise method for the construction of diverse α-aryl (α-cyclohexenyl) quaternary carbon stereogenic centers with good stereoselectivities. 相似文献
77.
A Selective C−H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine
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Sunil K. Sundalam Aleksandra Nilova Thomas L. Seidl Prof. Dr. David R. Stuart 《Angewandte Chemie (International ed. in English)》2016,55(29):8431-8434
Described here is an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts. The iodonium salts are prepared in a single pot from either commercially available aryl iodides or arylboronic acids. The aryne intermediates are generated by ortho‐C?H deprotonation of aryl(mesityl)iodonium salt with a commercially available amide base and trapped in a cycloaddition reaction with furan in moderate to good yields. Coupling partners for the aryne intermediates beyond furan are also described, including benzyl azide and alicyclic amine nucleophiles. The regio‐ and chemoselectivity of this reaction is discussed and evidence for the spectator aryl ligand of the iodonium salt as a critical control element in selectivity is presented. 相似文献
78.
Dr. José‐Antonio García‐López Dr. Meliha Çetin Prof. Michael F. Greaney 《Angewandte Chemie (International ed. in English)》2015,54(7):2156-2159
Arynes participate in three‐component coupling reactions with N, S, P, and Se functionalities to yield 1,2‐heteroatom‐difunctionalized arenes. Using 2‐iodophenyl arylsulfonates as benzyne precursors, we could effectively add magnesiated S‐, Se‐, and N‐nucleophilic components to the strained triple bond. In the same pot, addition of electrophilic N, S, or P reagents and a copper(I) catalyst trapped the intermediate aryl Grignard to produce a variety of 1,2‐difunctionalized arenes. 相似文献
79.
Dr. Guillaume Dauvergne Dr. Jean-Valère Naubron Dr. Michel Giorgi Prof. Dr. Xavier Bugaut Prof. Dr. Jean Rodriguez Dr. Yannick Carissan Dr. Yoann Coquerel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(68):e202202473
The synthetic equivalents of the enantiopure binaphthyl bis(aryne) atropisomers derived from BINOL (1,1′-bi-2,2′-naphtol) featuring a stereogenic axis vicinal to the two reactive triple bonds can be generated for the first time in solution in an enantiospecific manner. Using a two-step sequence based on the bidirectional [4+2] cycloaddition of furan derivatives followed by an aromatizative deoxygenation reaction, several 9,9’-bianthracenyl-based atropisomers could be prepared enantiospecifically in high enantiomeric purity. Alternatively, bidirectional reactions with anthracene, 2-bromostyrene, and perylene as the arynophiles afforded very congested bis(benzotriptycene), bis(tetraphene) and bis(anthra[1,2,3,4-ghi]perylene) nanocarbon atropisomers in equally high enantiomeric purity. In complement, cross reactions with two different arynophiles revealed possible. The unusual atropisomer prototypes described in this study open the way to enantiopure nanographene atropisomers designed for functions. 相似文献
80.