28406-56-6Relevant academic research and scientific papers
Mono- and dialkylations of pyrrole at C2 and C5 positions by nucleophilic substitution reaction in ionic liquid
Jorapur, Yogesh R.,Lee, Chang-Hee,Chi, Dae Yoon
, p. 1231 - 1234 (2005)
(Chemical Equation Presented) A novel ionic liquid methodology for pyrrole C-alkylation is described. The pyrrole alkylation is achieved with various simple alkyl halides and mesylates selectively at C2 and C5 positions in good yields with minimal byproducts under relatively mild conditions in various ionic liquids. 2-(3-Phenylpropyl)pyrrole (2a) was synthesized from pyrrole and 1-bromo-3-phenylpropane in a mixture solvent system, [bmim][SbF6] and CH3CN, in 81% yield at 115°C for 44 h with 5% yield of dialkylated compound 3a.
Synthesis and Photophysical Properties of Aza[n]helicenes
Upadhyay, Gourav M.,Talele, Harish R.,Bedekar, Ashutosh V.
, p. 7751 - 7759 (2016)
Synthesis and study of aza[7]helicene and aza[9]helicene is presented in this paper. Photo-dehydrocyclization of the 3,6-bis-styryl derivative of carbazole leading to sterically less demanding aza[7]helicene resulted in smooth reaction, and only the desired angular-angular product was detected. However, in the case of aza[9]helicene, along with the expected angular-angular cyclization, three other products involving linear mode of cyclization were also isolated and characterized. In this case, the helical compound aza[9]helicene was predominantly formed at lower concentration while the other isomers were obtained at higher concentration. All of the compounds formed by angular-angular, angular-linear, and linear-linear modes of cyclization were fully characterized, and their photophysical properties were investigated.
Photochemistry of 1,2-Dibromoethyl Arenes
Zhang, Bing,Pandit, C. R.,McGimpsey, W. Grant
, p. 7022 - 7028 (1994)
UV laser photolysis of 2-(1,2-dibromoethyl)naphthalene in benzene and acetonitrile results in C-Br homolytic bond cleavage via the singlet and possibly the triplet manifolds.Cleavage produces a bromine atom, Br., and the 2-bromo-1-(2-naphthyl)ethyl radical.In benzene, the presence of Br. is indicated by formation of the Br.-benzene ?-complex, while in acetonitrile with added Br-, Br2.- is produced.In addition to these two transient probes, the formation of acidic solutions following photolysis in the presence of a H atom donor is also an indication of Br. generation.The debromination quantum yield was determined by quantifying the formation of both Br2.-ΦBr. = 0.87 +/- 0.10, and acid ΦH+ = 0.85 +/- 0.14.The difference between these values and those obtained for other vicinal dibromides (ΦBr. > 2) which undergo photochemical debromination followed by facile thermal C-Br cleavage is attributed to the greater stability of the 2-bromo-1-(2-naphthyl)ethyl radical relative to 2-vinylnaphthalene, the product formed by loss of the second Br..Photolysis of the 2-bromo-1-(2-naphthyl)ethyl radical using a second laser pulse leads to further C-Br cleavage resulting in enhanced production of 2-vinylnaphthalene.UV laser photolysis of 2-bromo-9-(1,2-dibromoethyl)anthracene also causes C-Br cleavage resulting in the production of Br. and the 2-bromo-1-(2-bromo-9-anthryl)ethyl radical.The efficiency of debromination was lower in this compound (ΦBr. 0.45 +/- 0.10; ΦH+ = 0.48 +/- 0.11) than for the naphthalene compound because of competition between cleavage from the singlet manifold and intersystem crossing to a low-energy unreactive triplet state.Like the naphthalene analog, laser photolysis of the anthrylathyl radical leads to further debromination.Both radicals exhibit unusual stability in the presence of oxygen.
Photoredox Catalyzed Sulfonylation of Multisubstituted Allenes with Ru(bpy)3Cl2 or Rhodamine B
Chen, Jingyun,Chen, Shufang,Jiang, Jun,Lu, Qianqian,Shi, Liyang,Xu, Zekun,Yimei, Zhao
supporting information, (2021/11/09)
A highly regio- and stereoselective sulfonylation of allenes was developed that provided direct access to α, β-substituted unsaturated sulfone. By means of visible-light photoredox catalysis, the free radicals produced by p-toluenesulfonic acid reacted with multisubstituted allenes to obtain Markovnikov-type vinyl sulfones with Ru(bpy)3Cl2 or Rhodamine B as photocatalyst. The yield of this reaction could reach up to 91%. A series of unsaturated sulfones would be used for further transformation to some valuable compounds.
Functionalized styrene synthesis via palladium-catalyzed C[sbnd]C cleavage of aryl ketones
Dai, Hui-Xiong,Wang, Xing,Wang, Zhen-Yu,Xu, Hui,Zhang, Xu
supporting information, (2022/03/31)
We report herein the synthesis of functionalized styrenes via palladium-catalyzed Suzuki–Miyaura cross-coupling reaction between aryl ketone derivatives and potassium vinyltrifluoroborate. The employment of pyridine-oxazoline ligand was the key to the cleavage of unstrained C[sbnd]C bond. A variety of functional groups and biologically important moleculars were well tolerated. The orthogonal Suzuki–Miyaura coupling demonstrated the synthetic practicability.
Palladium-Catalyzed Benzylic Silylation of Diarylmethyl Carbonates with Silylboranes under Base-Free Conditions
Asai, Kento,Hirano, Koji,Miura, Masahiro
supporting information, (2022/02/19)
A palladium-catalyzed benzylic silylation of diarylmethyl carbonates with silylboranes has been developed. The reaction proceeds smoothly even under external base-free conditions, and the corresponding benzylic silanes are formed in good to high yields. The obtained benzyl silane derivatives can work as the benzylic nucleophiles by the action of a suitable fluoride source and react with some carbon electrophiles to deliver the corresponding benzylic C?C cross-coupled products. Additionally, while still preliminary, the allylic silylation of the isoelectronic allylic carbonates is also achieved.
Copper-Catalyzed Sulfonylation of Cyclobutanone Oxime Esters with Sulfonyl Hydrazides
Dong, Bingbing,Lu, Jiansha,Bao, Honghao,Zhang, Yuanyuan,Liu, Yingguo,Leng, Yuting
supporting information, p. 3769 - 3776 (2021/07/14)
A copper-catalyzed radical cross-coupling of cyclobutanone oxime esters with sulfonyl hydrazides has been developed. The copper-based catalytic system proved crucial for cleavage of the C-C bond of cyclobutanone oximes and for selective C-S bond-formation involving persistent sulfonyl-metal radical intermediates. This protocol is distinguished by the low-cost catalytic system, which does not require ligand, base, or toxic cyanide salt, and by the use of readily accessible starting materials, as well as broad substrate scope, providing an efficient approach to various diversely substituted cyano-containing sulfones.
Electrochemistry enabled selective vicinal fluorosulfenylation and fluorosulfoxidation of alkenes
Jiang, Yimin,Shi, Zhaojiang,Wu, Jinnan,Wu, Shaofen,Ye, Keyin,Yu, Yi,Yuan, Yaofeng
supporting information, (2021/11/17)
Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science. The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H2O in the reaction mixture.
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Arylketones as Aryl Donors in Palladium-Catalyzed Suzuki-Miyaura Couplings
Wang, Zhen-Yu,Ma, Biao,Xu, Hui,Wang, Xing,Zhang, Xu,Dai, Hui-Xiong
, p. 8291 - 8295 (2021/11/13)
Herein, we report the arylation, alkylation, and alkenylation of aryl ketones via a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction. The use of the pyridine-oxazoline ligand is the key to the cleavage of the unstrained C-C bond. The late-stage arylation of aryl ketones derived from drugs and natural products demonstrated the synthetic utility of this protocol.
