59156-10-4Relevant academic research and scientific papers
Carbazole based Electron Donor Acceptor (EDA) catalysis for the synthesis of biaryl and aryl-heteroaryl compounds
Annes, Sesuraj Babiola,Ramesh, Subburethinam,Saravanan, Subramanian,Saritha, Rajendhiran
supporting information, p. 2510 - 2515 (2020/04/15)
A highly regioselective, carbazole based Electron Donor Acceptor (EDA) catalyzed synthesis of biaryl and aryl-heteroaryl compounds is described. Various indole and carbazole derivatives were screened for the Homolytic Aromatic Substitution (HAS) reaction. Tetrahydrocarbazole (THC) was very efficient for the HAS transformation and proceeded via a complex formation between diazonium salt and electron rich tetrahydrocarbazole. The UV-Vis spectroscopy technique has been used to confirm the complex formation. The in situ generated EDA complex even in a catalytic amount is found to be efficient for the Single Electron Transfer (SET) process without any photoactivation. Biaryl compounds, 2-phenylfuran, 2-phenylthiophene, and 2-phenylpyrrole and bioactive compounds such as dantrolene and canagliflozin have been synthesized in moderate to excellent yields.
Transition-Metal-Free Synthesis of Heterobiaryls through 1,2-Migration of Boronate Complex
Paul, Swagata,Das, Kanak Kanti,Manna, Samir,Panda, Santanu
supporting information, p. 1922 - 1927 (2020/02/04)
The synthesis of a diverse range of heterobiaryls has been achieved by a transition-metal-free sp2–sp2 cross-coupling strategy using lithiated heterocycle, aryl or heteroaryl boronic ester and an electrophilic halogen source. The construction of heterobiaryls was carried out through electrophilic activation of the aryl–heteroaryl boronate complex, which triggered 1,2-migration from boron to the carbon atom. Subsequent oxidation of the intermediate boronic ester afforded heterobiaryls in good yield. A comprehensive 11B NMR study has been conducted to support the mechanism. The cross coupling between two nucleophilic cross coupling partners without transition metals reveals a reliable manifold to procure heterobiaryls in good yields. Various heterocycles like furan, thiophene, benzofuran, benzothiophene, and indole are well tolerated. Finally, we have successfully demonstrated the gram scale synthesis of the intermediates for an anticancer drug and OLED material using our methodology.
N,S-chelating triazole-thioether ligand for highly efficient palladium-catalyzed Suzuki reaction
Yan, Qiong,Zheng, Lei,Li, Miaomiao,Chen, Yunfeng
, p. 101 - 105 (2019/07/19)
1,2,3-Triazole-thioether compounds could serve as efficient ligands for Pd-catalyzed Suzuki reactions of various aryl iodides, bromides and chlorides. The reactions feature wide substrate scope and mild reaction conditions. Besides, shorter reaction time, lower catalyst loadings and quantitative yields with a turnover-frequency (TOF) value of up to 11,880 h?1 are other advantageous of this attractive protocol. The crystal structure analyses and computational studies revealed that the higher catalytic activity of the corresponding chelated palladium complex ascribed to the lower energy gap and the lower redox potential.
Light-Induced C-H Arylation of (Hetero)arenes by in Situ Generated Diazo Anhydrides
Cantillo, David,Mateos, Carlos,Rincon, Juan A.,De Frutos, Oscar,Kappe, C. Oliver
supporting information, p. 12894 - 12898 (2015/09/07)
Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time.
Structural and reactivity insights in Mg-Zn hybrid chemistry: Zn-I exchange and Pd-catalysed cross-coupling applications of aromatic substrates
Bluemke, Tobias D.,Clegg, William,Garcia-Alvarez, Pablo,Kennedy, Alan R.,Koszinowski, Konrad,McCall, Matthew D.,Russo, Luca,Hevia, Eva
, p. 3552 - 3562 (2014/08/18)
Expanding the synthetic potential of Mg-Zn hybrid organyl reagents (generated via transmetallation reactions), this study uncovers a versatile approach, involving a sequence of direct Zn-I exchange and Pd catalysed cross-coupling reactions which grants access to a wide range of asymmetric bis(aryls). By combining X-ray crystallography with ESI-MS and non-deuterium NMR spectroscopic studies, new light is shed on the heterobimetallic constitution of the intriguing organometallic species [(THF)4MgCl 2Zn(tBu)Cl] (1) and [{Mg2Cl3(THF) 6}+{ZntBu3}-] (2), formed through transmetallation of tBuMgCl with n equivalent amounts of ZnCl2 (n = 1 and 3 respectively). Operating by cooperative effects, alkyl-rich hybrid 2 can effectively promote direct Zn-I exchange reactions with aromatic halides in short periods of time at room temperature in THF solution. The structural elucidation of key organometallic intermediates involved in some of these Zn-I exchanges, provides new reactivity insights into how these bimetallic systems operate. Thus, while the reaction of 2 with 3 equivalents of 2-iodoanisole (3b) gives magnesium dizincate [{Mg(THF)6}2+{Zn(o-C 6H4-OMe)3}2-] (4) which demonstrates the 3-fold activation of the tBu groups attached to Zn in 2, using 2-iodobenzonitrile (3i), only two tBu groups react with the substrate, affording [(THF)4MgCl(NC-o-C6H4)ZnI(o-C 6H4-CN)(THF)] (7). In 7 Mg and Zn are connected by an aryl bridge, suggesting that the formation of contacted ion-pair hybrids may have a deactivating effect on the outcome of the Zn-I exchange process. A wide range of homoleptic tris(aryl) zincate intermediates have been prepared in situ and used as precursors in Pd catalysed cross-coupling reactions, affording bis(aryls) 6a-s in excellent yields under mild reaction conditions without the need of any additive or polar cosolvent such as NMP or DMI.
Selective Mg insertion into substituted mono- and dichloro arenes in the presence of LiCl: A new preparation of boscalid
Dunst, Cora,Knochel, Paul
experimental part, p. 2064 - 2068 (2011/10/09)
The LiCl-mediated Mg insertion into polysubstituted aryl chlorides bearing up to three chloro substituents in ortho or meta position selectively leads to Grignard reagents which readily react with various electrophiles. As an application, we have developed a new formal synthesis of boscalid. Georg Thieme Verlag Stuttgart - New York.
Synthesis of functionalized 2-arylthiophenes with triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium catalysis
Rao, Maddali L. N.,Banerjee, Debasis,Dhanorkar, Ritesh J.
supporting information; experimental part, p. 1324 - 1330 (2011/07/07)
Atom-efficient cross-coupling reactions of functionalized 2-bromo- and 2-iodothiophenes have been demonstrated using triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium-catalyzed conditions. These couplings with various functionalized triarylbismuths proceeded smoothly to afford the corresponding functionalized 2-arylthiophenes in high yields. Georg Thieme Verlag Stuttgart · New York.
The preparations and some properties of mixed aryl-thienyl oligomers and polymers
Pelter, Andrew,Jenkins, Ieuan,Jones, D. Elfyn
, p. 10357 - 10400 (2007/10/03)
The syntheses by transition metal coupling reactions of a large number of oligomers constructed from benzene and thiophene rings are described. The first use of arylcadmium chlorides for such coupling reactions is reported. The routes chosen allow for rational variation in the modes of linkage, the substitution and the proportions of the two units. The benzene and thiophene rings are always joined in a known order and may bear a wide variety of regularly spaced functional groups. Additionally the shape of the oligomers may be varied at will. In all cases p-type doping with iodine or ferric chloride leads to large enhancements in conductivity.
