2235-83-8Relevant academic research and scientific papers
B(C6F5)3-Catalyzed Diastereoselective Formal (4 + 1)-Cycloaddition of Vinylcyclopropanes and Et2SiH2
Long, Peng-Wei,Oestreich, Martin
supporting information, p. 4834 - 4837 (2021/06/28)
A formal (4 + 1)-cycloaddition of vinylcyclopropanes and Et2SiH2 to afford 3,4-disubstituted silolanes is reported. The reaction sequence commences with the known B(C6F5)3-catalyzed alkene hydrosilylation with dihydrosilanes. Cleavage of the remaining Si-H bond in the hydrosilylation product assisted by B(C6F5)3 leads to formation of a cyclopropane-stabilized silylium ion. The activated cyclopropane ring is then opened by the in situ-generated borohydride accompanied by ring closure to the silolane. The diastereoselectivity is rationalized by a mechanistic model.
Cobalt-Catalyzed Radical Hydroamination of Alkenes with N-Fluorobenzenesulfonimides
Lv, Guowei,Meng, Qi,Qin, Tao,Xiong, Tao,Zhang, Ge,Zhang, Qian
supporting information, p. 25949 - 25957 (2021/11/01)
An efficient and general radical hydroamination of alkenes using Co(salen) as catalyst, N-fluorobenzenesulfonimide (NFSI) and its analogues as both nitrogen source and oxidant was successfully disclosed. A variety of alkenes, including aliphatic alkenes, styrenes, α, β-unsaturated esters, amides, acids, as well as enones, were all compatible to provide desired amination products. Mechanistic experiments suggest that the reaction underwent a metal-hydride-mediated hydrogen atom transfer (HAT) with alkene, followed by a pivotal catalyst controlled SN2-like pathway between in situ generated organocobalt(IV) species and nitrogen-based nucleophiles. Moreover, by virtue of modified chiral cobalt(II)-salen catalyst, an unprecedented asymmetric version was also achieved with good to excellent level of enantiocontrol. This novel asymmetric radical C?N bond construction opens a new door for the challenging asymmetric radical hydrofunctionalization.
Method for preparing carbonyl compound through oxidative cleavage of visible light excitation aqueous solution quantum dot catalytic olefin compound
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Paragraph 0039, (2021/11/10)
The invention provides a method for preparing carbonyl compounds through oxidative cleavage of a visible light excitation aqueous solution quantum dot catalytic olefin compound. Belong to photocatalysis synthesis technical field. To the method, an aqueous solution quantum dot is used as a photocatalyst, and an aqueous solution quantum dot activated molecular oxygen catalytic oxidation aromatic alkene compound is excited by visible light to be cracked to prepare a carbonyl compound. Low-loading capacity is used, a simple aqueous solution quantum dot is used as a catalyst, the yield of the carbonyl compound is high, TON more than ten millions are obtained. The reaction conditions are mild, water serves as a main solvent for the reaction, and the carbonyl compound can be obtained by catalytic olefin compound oxidation cracking without addition of a cocatalyst or the like. The method is simple to operate, wide in substrate range and low in cost.
Direct Access to Isotopically Labeled Aliphatic Ketones Mediated by Nickel(I) Activation
Donslund, Aske S.,Pedersen, Simon S.,Gaardbo, Cecilie,Neumann, Karoline T.,Kingston, Lee,Elmore, Charles S.,Skrydstrup, Troels
supporting information, p. 8099 - 8103 (2020/03/16)
An extensive range of functionalized aliphatic ketones with good functional-group tolerance has been prepared by a NiI-promoted coupling of either primary or secondary alkyl iodides with NN2 pincer NiII-acyl complexes. The latter were easily accessed from the corresponding NiII-alkyl complexes with stoichiometric CO. This Ni-mediated carbonylative coupling is adaptable to late-stage carbon isotope labeling, as illustrated by the preparation of isotopically labelled pharmaceuticals. Preliminary investigations suggest the intermediacy of carbon-centered radicals.
Aldehydes as Alkylating Agents for Ketones
Runikhina, Sofiya A.,Afanasyev, Oleg I.,Biriukov, Klim,Perekalin, Dmitry S.,Klussmann, Martin,Chusov, Denis
supporting information, p. 16225 - 16229 (2019/11/22)
Common and non-toxic aldehydes are proposed as reagents for alkylation of ketones instead of carcinogenic alkyl halides. The developed reductive alkylation reaction proceeds in the presence of the commercially available ruthenium catalyst [(cymene)RuCl2]2 (as low as 250 ppm) and carbon monoxide as the reducing agent. The reaction works well for a broad substrate scope, including aromatic and aliphatic aldehydes and ketones. It can be carried out without a solvent and often gives nearly quantitative yields of the products. This straightforward and cost-effective method is promising not only for laboratory application but also for industry, which produces carbon monoxide as a large-scale waste product.
Iminyl Radical-Triggered Intermolecular Distal C(sp3)-H Heteroarylation via 1,5-Hydrogen-Atom Transfer (HAT) Cascade
Gu, Yu-Rui,Duan, Xin-Hua,Chen, Li,Ma, Zhi-Yong,Gao, Pin,Guo, Li-Na
supporting information, p. 917 - 920 (2019/02/14)
An efficient iron-catalyzed intermolecular remote C(sp3)-H heteroarylation of alkyl ketones has been developed via an iminyl radical-triggered 1,5-hydrogen-atom transfer (HAT) cascade. This protocol was amenable to a wide variety of alkyl ketones and heteroaryls, thus providing a straightforward method for the late-stage functionalization of alkylketones and heteroaryls.
A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters
Lima, Fabio,Sharma, Upendra K.,Grunenberg, Lars,Saha, Debasmita,Johannsen, Sandra,Sedelmeier, Joerg,Van der Eycken, Erik V.,Ley, Steven V.
supporting information, p. 15136 - 15140 (2017/11/20)
We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron-deficient olefins via radical addition to efficiently form C?C coupled products in a redox-neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.
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.
One-pot synthesis of benzene-fused medium-ring ketones: Gold catalysis-enabled enolate umpolung reactivity
Xu, Zhou,Chen, Hongyi,Wang, Zhixun,Ying, Anguo,Zhang, Liming
, p. 5515 - 5518 (2016/05/24)
Enolate umpolung reactivities offer valuable and potentially unique alternatives over the enolate counterparts for the construction of ubiquitous carbonyl compounds. We disclose here that N-alkenoxypyridinium salts, generated readily upon gold-catalyzed additions of protonated pyridine N-oxide to C-C triple bonds of unactivated terminal alkynes, display versatile enolate umpolung chemistry upon heating and react with tethered arene nucleophiles in an SN2′ manner. In a synthetically efficient one-pot, two-step process, this chemistry enables expedient preparation of valuable benzo-fused seven-/eight-membered cyclic ketones, including those of O-/Nheterocycles, from easily accessible aryl-substituted linear alkyne substrates. The reaction yields can be up to 87%.
Decarboxylative Cross-Electrophile Coupling of N-Hydroxyphthalimide Esters with Aryl Iodides
Huihui, Kierra M. M.,Caputo, Jill A.,Melchor, Zulema,Olivares, Astrid M.,Spiewak, Amanda M.,Johnson, Keywan A.,Dibenedetto, Tarah A.,Kim, Seoyoung,Ackerman, Laura K. G.,Weix, Daniel J.
, p. 5016 - 5019 (2016/05/19)
A new method for the decarboxylative coupling of alkyl N-hydroxyphthalimide esters (NHP esters) with aryl iodides is presented. In contrast to previous studies that form alkyl radicals from carboxylic acid derivatives, no photocatalyst, light, or arylmetal reagent is needed, only nickel and a reducing agent (Zn). Methyl, primary, and secondary alkyl groups can all be coupled in good yield (77% ave yield). One coupling with an acid chloride is also presented. Stoichiometric reactions of (dtbbpy)Ni(2-tolyl)I with an NHP ester show for the first time that arylnickel(II) complexes can directly react with NHP esters to form alkylated arenes.
