38328-16-4Relevant academic research and scientific papers
Vinyl Sulfonium Salts as the Radical Acceptor for Metal-Free Decarboxylative Alkenylation
Zhang, Yu-Lan,Yang, Lei,Wu, Jie,Zhu, Chunyin,Wang, Peng
, p. 7768 - 7772 (2020/10/09)
Vinyl sulfonium salts typically act as an electrophilic Michael acceptor, thus initiating many tandem cyclization reactions. Herein, we disclosed the novel reactivity of vinyl sulfonium salts as a radical acceptor. Using redox-active ester as an alkyl rad
Visible Light-Driven, Room Temperature Heck-Type Reaction of Alkyl Halides with Styrene Derivatives Catalyzed by B12 Complex
Chen, Li,Hisaeda, Yoshio,Shimakoshi, Hisashi
, p. 2877 - 2884 (2019/04/03)
A visible light driven Heck-type coupling reaction of alkyl halides with styrene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ru(bpy)3]Cl2 photosensitizer at room temperature is reported. The catalytic efficiencies of the B12 catalyst were compared to that of other cobalt complexes such as cobaloxime. Various control experiments supported a radical-based mechanism similar to those for typical B12 model reactions. A unique coupling reaction combined with 1,2-migration of the functional group is also reported. Mild reaction conditions using an environmentally benign cobalt catalyst derived from the natural B12 provided a practical protocol for the synthetic organic chemistry of the B12 catalyzed reaction system. (Figure presented.).
Conversion of Carbonyl Compounds to Olefins via Enolate Intermediate
Cao, Zhi-Chao,Xu, Pei-Lin,Luo, Qin-Yu,Li, Xiao-Lei,Yu, Da-Gang,Fang, Huayi,Shi, Zhang-Jie
supporting information, p. 781 - 785 (2019/06/24)
A general and efficient protocol to synthesize substituted olefins from carbonyl compounds via nickel catalyzed C—O activation of enolates was developed. Besides ketones, aldehydes were also suitable substrates for the presented catalytic system to produce di- or tri- substituted olefins. It is worth noting that this approach exhibited good tolerance to highly reactive tertiary alcohols, which could not survive in other reported routes for converting carbonyl compounds to olefins. This method also showed good regio- and stereo-selectivity for olefin products. Preliminary mechanistic studies indicated that the reaction was accomplished through nickel catalyzed C—O activation of enolates, thus offering helpful contribution to current enol chemistry.
Allylic Arylation of 1,3-Dienes via Hydroboration/Migrative Suzuki-Miyaura Cross-Coupling Reactions
Zhang, Xiao-Ming,Yang, Jie,Zhuang, Qing-Bo,Tu, Yong-Qiang,Chen, Zongyuan,Shao, Hui,Wang, Shao-Hua,Zhang, Fu-Min
, p. 6094 - 6099 (2018/06/11)
The hydroboration/Pd-catalyzed migrative Suzuki-Miyaura cross-coupling of 1,3-dienes with electron-deficient aryl halides has been developed, which enables the synthesis of branched allylarenes directly from primary homoallylic alkyl boranes. A ligand-tuned linear- or branch-selective coupling for these aryl halides has also been achieved.
Borata-Wittig olefination reactions of ketones, carboxylic esters and amides with bis(pentafluorophenyl)borata-alkene reagents
Wang, Tongdao,Kohrt, Sonja,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
supporting information, p. 6223 - 6232 (2017/08/02)
The strongly electrophilic borane derivative amino-CH2CH2CH2-B(C6F5)26 was α-CH deprotonated with LiTMP to give the borata-alkene {[amino-(CH2)2-CHB(C6F5)2-][Li+]}29 which underwent facile [2 + 2] cycloaddition reactions with benzophenone or fluorenone to yield the respective 1,2-oxaboretanides 11a,b. Compounds 9 and 11 were characterized by the X-ray diffraction. Thermolysis or hydrolysis of compounds 11a,b gave the corresponding borata-Wittig olefination products 12a,b. A variety of R-CH2-CH2-B(C6F5)2 boranes (conveniently generated by hydroboration of terminal alkenes R-CHCH2 with Piers' borane [HB(C6F5)2]) were analogously deprotonated to give the respective borata-alkenes 16a-e (R: Ph-CH2-, nC4H9, tBu, Cy, PhCH2CH2-). They underwent "non-classical" borata-Wittig olefination reactions with ethylformate to give the respective enolether carbonylation products, or their C1-elongated aldehydes (after hydrolysis). The borata-alkene [Ph-(CH2)2-CHB(C6F5)2-] [Li+HTMP] (16a) gave the respective "non-classical" borata-Wittig olefination products, the enolethers 25a,b and 27, respectively, upon treatment with methyl- or ethyl acetate or γ-butyrolactone.
Hypervalent iodine reagents enable chemoselective deboronative/decarboxylative alkenylation by photoredox catalysis
Huang, Hanchu,Jia, Kunfang,Chen, Yiyun
, p. 1881 - 1884 (2015/02/19)
Chemoselective C(sp3)-C(sp2) coupling reactions under mild reaction conditions are useful for synthesizing alkyl-substituted alkenes having sensitive functional groups. Reported here is a visible-light-induced chemoselective alkenylation through a deboronation/decarboxylation sequence under neutral aqueous reaction conditions at room temperature. This reaction represents the first hypervalent-iodineenabled radical decarboxylative alkenylation reaction, and a novel benziodoxole-vinyl carboxylic acid reaction intermediate was isolated. This C(sp3/sup>)-C(sp2) coupling reaction leads to aryl-and acyl-substituted alkenes containing various sensitive functional groups. The excellent chemoselectivity, stable reactants, and neutral aqueous reaction conditions of the reaction suggest future biomolecule applications.
Copper-catalyzed oxidative heck reactions between alkyltrifluoroborates and vinyl arenes
Liwosz, Timothy W.,Chemler, Sherry R.
supporting information, p. 3034 - 3037 (2013/07/26)
We report herein that potassium alkyltrifluoroborates can be utilized in oxidative Heck-type reactions with vinyl arenes. The reaction is catalyzed by a Cu(OTf)2/1,10-phenanthroline with MnO2 as the stoichiometric oxidant. In addition to the alkyl Heck, amination, esterification, and dimerization reactions of alkyltrifluoroborates are demonstrated under analogous reaction conditions. Evidence for an alkyl radical intermediate is presented.
Structural effects in radical clocks and mechanisms of grignard reagent formation: Special effect of a phenyl substituent in a radical clock when the crossroads of selectivity is at a metal/solution interface
Hazimeh, Hassan,Mattalia, Jean-Marc,Marchi-Delapierre, Caroline,Kanoufi, Frederic,Combellas, Catherine,Chanon, Michel
experimental part, p. 2775 - 2787 (2009/08/16)
A large class of radical clocks is based on the intramolecular trapping of a reactive radical by a suitably located, unsaturated system. Depending on the substituents present on this unsaturated system, the rate of cyclisation may vary drastically. This property has been repeatedly used, to diagnose the participation of very short-lived radicals in the mechanisms of a wide variety of reactions. For reactions occurring in homogeneous solution, a phenyl substituent capable of stabilizing the radical formed during the act of trapping has been one of the most widely used tools of this type. During study of the mechanisms of formation of Grignard reagents - reactions that occur at the interface of the metal and the solution - the phenyl substituent displayed a specific new behaviour pattern. Besides its stabilizing role, it was also able to play the role of mediator in redox catalysis of electron transfer. In this case, the first events on the pathway to the Grignard reagents involve a cascade of three (one intermolecular followed by two intramolecular) electron transfers. Introduction of a p-methoxy substituent on the phenyl ring, making the phenyl group a poorer electron acceptor, suppresses this specific second role. Applied to the mechanism of Grignard reagent formation, this p-methoxy effect is consistent with a triggering mechanistic act of electron transfer from the metal to the aryl halide rather than with a concerted oxidative addition. A similar change in selectivity is observed, when a p-methoxy group is introduced onto a phenyl group that also bears a halogen, but its origin is different: this effect is associated with the shortening of the lifetime of the radical anion formed by the triggering electron transfer. These observations reemphasise our earlier proposals to use concepts originating from, electrochemical kinetics to explain, the selectivities of reactions occurring at metal/solution interfaces. This conjecture could possibly hold for any interface where the diffusion of reactive species plays a role in the settling of selectivity. These concepts emphasise the necessity to consider, for each reactive species, their average distance of diffusion away from the metal/solution interface. Wiley-VCH Verlag GmbH & Co. KGaA.
Lewis acid BF3·OEt2-catalyzed Friedel-Crafts reaction of methylenecyclopropanes with arenes
Huang, Jin-Wen,Shi, Min
, p. 9343 - 9347 (2007/10/03)
Methylenecyclopropanes react with various arenes to give the Friedel-Crafts reaction products in good yields in the presence of Lewis acid BF3·OEt2.
