2949-26-0Relevant academic research and scientific papers
Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
Kinoshita, Hidenori,Kumaki, Wataru,Miura, Katsukiyo
supporting information, (2022/03/07)
Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
Iron-Catalyzed Vinylzincation of Terminal Alkynes
Huang, Qiang,Su, Yu-Xuan,Sun, Wei,Hu, Meng-Yang,Wang, Wei-Na,Zhu, Shou-Fei
, p. 515 - 526 (2022/01/08)
Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C–H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.
Polycyclic aromatic hydrocarbon-substituted push-pull chromophores: An investigation of optoelectronic and nonlinear optical properties using experimental and theoretical approaches
Dengiz, ?a?atay
, p. 1375 - 1390 (2021/10/26)
A series of new push-pull chromophores were synthesized in moderate to very high yields (65%-97%) by treating TCNE and TCNQ with alkynes substituted by electron-rich diethylaniline and polycyclic aromatic hydrocarbons. Some of the chromophores exhibit strong intramolecular charge-transfer bands in the near-IR region with λmax values between 695 and 749 nm. With the help of experimental and theoretical analysis, it is concluded that the trend in λmax values is affected by PAH substituents sterically, not electronically. Steric constraints led to the increased dihedral angles, reducing conjugation efficiencies. The absorption properties of push-pull compounds have been investigated in solvents possessing different polarities. All chromophores exhibited positive solvatochromism. As an additional proof of efficient charge-transfer in push-pull chromophores, quinoid character (dr) values were predicted using calculated bond lengths. Remarkably, substantial dr values (0.045-0.049) were predicted for donor diethylaniline rings in all compounds. The effects of various polycyclic aromatic hydrocarbons on optical and nonlinear optical properties were also studied by computational methods. Several parameters, such as band gaps, Mulliken electronegativity, chemical hardness and softness, dipole moments, average polarizability, first hyperpolarizability, were predicted for chromophores at the B3LYP/6-31++G(d,p) level of theory. The predicted first hyperpolarizability β(tot) values vary between 198 to 538 × 10-30 esu for the reported push-pull chromophores in this study. The highest predicted β(tot) value in this study is 537.842 × 10-30 esu, 8150 times larger than the predicted β(tot) value of benchmark NLO material urea, suggests possible utilization of these chromophores in NLO devices. The charge-transfer character of the synthesized structures was further confirmed by HOMO-LUMO depictions and electrostatic potential maps.
1,2-Carbopentafluorophenylation of Alkynes: The Metallomimetic Pull-Push Reactivity of Tris(pentafluorophenyl)borane
Shibuya, Masatoshi,Matsuda, Miki,Yamamoto, Yoshihiko
supporting information, p. 8822 - 8831 (2021/05/21)
We report the novel single-step 1,2-dicarbofunctionalization of an arylacetylene with an allylsilane and tris(pentafluorophenyl)borane [B(C6F5)3] involving C?C bond formation with C?H bond scission at the β-position to the silicon atom of an allylsilane and B→C migration of a C6F5 group. The 1,2-carbopentafluorophenylation occurs smoothly without the requirement for a catalyst or heating. Mechanistic studies suggest that the metallomimetic “pull-push” reactivity of B(C6F5)3 imparts consecutive electrophilic and nucleophilic characteristics to the benzylic carbon of the arylacetylene. Subsequent photochemical 6π-electrocyclization affords tetrafluoronaphthalenes, which are important in the pharmaceutical and materials sciences. Owing to the unique reactivity of B(C6F5)3, the 1,2-carbopentafluorophenylation using 2-substituted furan proceeded with ring opening, and the reaction using silyl enolates formed a C?C bond with C?O bond scission at the silyloxy-substituted carbon.
Cu-mediated or metal-free alkylation of gem-dibromoalkenes with tertiary, secondary and primary alkyl Grignard reagents
Deng, Yupian,Zhang, Xuxue,Liu, Chuan,Cao, Song
, (2021/01/18)
A novel copper-mediated or transition-metal-free alkylation of gem-dibromoalkenes with tertiary, secondary and primary alkyl Grignard reagents was described. The outcomes of these reactions were found to be highly dependent on the reaction conditions and
Synthesis of alkynes under dry reaction conditions
Rao, Maddali L.N.,Shamim Islam, Sk
supporting information, (2021/04/19)
An easy synthetic method was developed under dry reaction conditions for the preparation of terminal alkynes from 1,1-dibromoalkenes and in the presence of succinimide which acts as a nucleophile and proton donor. It was demonstrated with the synthesis of a broad spectrum of terminal alkynes and extended to synthesize internal alkynes under tandem reaction conditions.
Tertiary amines acting as Alkyl radical equivalents enabled by a P/N heteroleptic Cu(I) photosensitizer
Zheng, Limeng,Jiang, Qinfang,Bao, Hanyang,Zhou, Bingwei,Luo, Shu-Ping,Jin, Hongwei,Wu, Huayue,Liu, Yunkui
, p. 8888 - 8893 (2020/11/30)
An unprecedented exploration of tertiary amines as alkyl radical equivalents for cross-coupling with aromatic alkynes to access allylarenes has been achieved by a P/N heteroleptic Cu(I)based photosensitizer under photoredox catalysis conditions. Mechanist
Perylene Bisimide and Naphthyl-Based Molecular Dyads: Hydrogen Bonds Driving Co-planarization and Anomalous Temperature-Response Fluorescence
Chou, Pi-Tai,Fang, Yu,Jiang, Qingwei,Liu, Fengyi,Liu, Ke,Shang, Congdi,Wang, Gang
supporting information, p. 8579 - 8585 (2020/03/24)
The origin of the positive temperature effect in fluorescence emission of a newly designed perylene bisimide (PBI) derivative with two naphthyl units containing ortho-methoxy group (NM) at its bay positions (PBI-2NM) was elucidated. A key point is the finding of a weak hydrogen bond (?1) between the methoxy group of the NM unit and a nearby hydrogen atom of the PBI core. It is the bonding that drives co-planarization of the different aromatic units, resulting in delocalization of the π-electrons of the compound as synthesized, inducing fluorescence quenching via intramolecular charge transfer (ICT). With increasing temperature, the co-planar structure could be distorted in part, resulting in a decreased degree of ICT, and hence leading to enhanced fluorescence emission. The unique positive temperature effect in emission induced by H-bond-driven co-planarization may pave a new avenue in designing functional molecular systems complementary to conventional methods.
Grignard-Reagent-Promoted Desulfonylation/Intramolecular Coupling for the Synthesis of 2-(1-Fluorovinyl)pyridines
Jiang, Gaoxi,Kang, Lei,Qian, Jinlong,Yang, Huameng,Zhang, Jinlong
supporting information, p. 9118 - 9122 (2020/12/02)
A novel process involving Grignard-reagent-promoted desulfonylation/intramolecular coupling of readily available α-fluoro-α,β-unsaturated-(2-pyridyl)sulfones was realized that provided a series of polysubstituted 2-(1-fluorovinyl)pyridines in good yields. The intrinsic coordination between pyridine and Mg(II) along with the "negative fluorine effect"of the substrates should play the key role for the smooth transformation in the absence of transition-metal catalysts.
Method for synthesizing 1,5-benzodiazepine compound
-
, (2019/12/25)
The invention discloses a method for synthesizing a 1,5-benzodiazepine compound. The method specifically comprises the following steps: dissolving a gold catalyst, an additive, alkyne of a formula IIshown in the specification, an o-phenylenediamine derivative of a formula III shown in the specification into an organic solvent, putting the solution into a pressure-resistant reaction tube, performing a stirring reaction for 6-24 hours at 25 DEG C so as to obtain a reaction liquid, and performing aftertreatment on the reaction liquid so as to obtain the 1,5-benzodiazepine compound of a formula IV shown in the specification, wherein the mass ratio of the gold catalyst of a formula I shown in the specification to the additive to the alkyne of the formula II shown in the specification to the o-phenylenediamine derivative of the formula III shown in the specification is (0.01-0.07):(0-0.1):(2.0-3.0):1. By adopting the method disclosed by the invention, a double-functional catalyst is used, the reaction can be performed under a room temperature condition, and thus energy consumption can be reduced; and the method has the advantages of being small in catalyst amount, high in yield, good insubstrate universality, simple and convenient in operation, and the like.
