21221-91-0Relevant academic research and scientific papers
(Hexaphenyltrimethylene)methane dication and related carbocations
Head, Nicholas J.,Olah, George A.,Prakash, G. K. Surya
, p. 11205 - 11210 (1995)
By ionization of the respective alkenediol (8a), the (hexaphenyltrimethylene)methane dication (2) has been prepared and found stable in solution under superacidic stable ion conditions (FSO3H/SO2CIF) up to at least -20 °C. The spectroscopic data and AMI theoretical modeling indicate that although the entire π-system is twisted, phenyl groups stabilize the positive charges in 2 to a similar degree as those in the trityl cation. The hexa-p-CF3 derivative of 2 was also observable but only at very low temperatures (-90 °C). Disruption of the 3-fold symmetry and reduction of the number of stabilizing phenyl rings even to five resulted in intramolecular allylation and subsequent formation of the corresponding indenyl cations. In all the cases studied no evidence for "Y-aromatic" stabilization was found.
En Route to Stimuli-Responsive Boron-, Nitrogen-, and Sulfur-Doped Polycyclic Aromatic Hydrocarbons
Hertz, Valentin M.,Massoth, Julian G.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
, p. 13181 - 13188 (2016)
Replacing both meso carbon atoms of the polycyclic aromatic hydrocarbon (PAH) bisanthene by boron atoms creates an efficient blue fluorophore with a strong electron-accepting character. The corresponding meso-B,S-doped bisanthene exhibits a solvent-dependent green-to-orange photoluminescence and undergoes a reversible reduction at E1/2= -2.06V (vs.FcH/FcH+. After oxidation of the sulfur atom, the resulting sulfoxide emits in the blue range of the spectrum, shows only negligible solvatochromism, and a reversible redox transition at E1/2= -1.74 V. Several related B, N- and B, S-containing PAHs have been prepared following the same modular synthetic procedure and are also described herein. In order to systematically compare their optoelectronic properties, all products have been investigated by cyclic voltammetry as well as UV/Vis absorption/emission spectroscopy.
Photo-induced phosphorus radical involved semipinacol rearrangement reaction: Highly synthesis of γ-oxo-phosphonates
Wang, Chunhai,Huang, Xiaoling,Liu, Xueting,Gao, Suqian,Zhao, Bin,Yang, Shangdong
supporting information, p. 677 - 680 (2019/08/27)
Hydroxyphosphoric acids display the unique biological activities, and they have some attractive prospects as clinical drug moleculars. Herein, a new approach for the synthesis of γ-oxo-phosphonates (the precursor of hydroxyphosphoric acid) has been established through the semipinacol rearrangement tactic involved the photo-induced phosphorus radical process. Most important, this transformation is avoid of the external oxidants, and occurs very well under the sunlight irradiation, meanwhile the γ-oxo-phosphonate was easily derivatized to obtain γ-hydroxyphosphoric acid, thus highlights the synthesis value of this method.
Water Phase, Room Temperature, Ligand-Free Suzuki–Miyaura Cross-Coupling: A Green Gateway to Aryl Ketones by C–N Bond Cleavage
Zhang, Yuqi,Wang, Zijia,Tang, Zhao,Luo, Zhongfeng,Wu, Hongxiang,Liu, Tingting,Zhu, Yulin,Zeng, Zhuo
, p. 1620 - 1628 (2020/03/04)
We report herein a green strategy for synthesis of aryl ketones from twisted amides by using Pd(OAc)2 as catalysts. This method shows high functional group tolerance to offer a variety of ketones in good yields under mild conditions (up to 94 %). Notably, this methodology demonstrates the first water phase, room temperature, ligand-free Suzuki–Miyaura coupling through C–N bond cleavage, which is environmentally friendly and might facilitate the development of amide based green chemistry.
Method for preparing symmetric diarylketone through catalytic oxidative carbonylation
-
Paragraph 0023; 0024; 0025; 0026; 0029, (2019/03/08)
The invention discloses a method for preparing symmetric diarylketone of a formula (I) as shown in the description. The method comprises the following steps: mixing arylboronic acid (II) (Ar-B(OH)2 (II)), a palladium catalyst, a promoter and an organic solvent in a reactor, introducing air and CO having a volume ratio of (7-19):1, reacting under the conditions of a pressure of 1-6 atm and a temperature of 30-80 DEG C for 8-16 hours, and performing after-treatment on the reaction solution, thereby obtaining the product symmetric diarylketone. According to the method disclosed by the invention,the air directly serves as an oxidizing agent to replace the O2 to be applied to oxidative carbonylation of the arylboronic acid, and the ratio of the air to CO is beyond an explosion limit. Therefore, the catalytic system is safe and economic. The palladium catalyst is small in dosage and simple in separation and can be recycled for several times. The method disclosed by the invention is mild inreaction condition, excellent in substrate suitability and high in yield.
Synthesis and Catalytic Evaluation of Phosphanylferrocene Ligands with Cationic Guanidinium Pendants and Varied Phosphane Substituents
Bárta, Ond?ej,Císa?ová, Ivana,Mieczyńska, Ewa,Trzeciak, Anna M.,?těpni?ka, Petr
, p. 4846 - 4854 (2019/12/03)
This contribution expands the still narrow class of functional ferrocene phosphanes with polar cationic groups, focusing on the synthesis and catalytic use of a series of phosphanylferrocene ligands bearing positively charged guanidinium tags, [R2PfcCH2NHC(NH2)2]Cl (3a–d), where fc = ferrocene-1,1′-diyl, R = isopropyl (a), cyclohexyl (b), phenyl (c), and 2-furyl (d). To probe the influence of phosphane substituents, these compounds were studied as supporting ligands in Pd-catalyzed Suzuki–Miyaura cross-coupling of acyl chlorides with arylboronic acids, in analogous coupling of aryl bromides with arylboronic acids, and in Rh-catalyzed hydroformylation of 1-hexene using trans-[RhCl(CO){R2PfcCH2NHC(NH2)2-κP}2]Cl2 complexes (4a–d) as pre-catalysts. The outcome of the cross-coupling reactions strongly depended on the starting materials, and no ligand generated a universally applicable catalyst when combined with Pd(OAc)2. In the hydroformylation reactions, the catalyst based on 4d led to lower conversions than all others, which performed rather similarly. Overall, the phenyl-substituted phosphane 3c emerged as a good compromise, giving rise to reasonably efficient and stable catalysts in most cases (except for Suzuki–Miyaura biaryl cross-couplings, wherein electron-rich alkylphosphanes performed better than 3c).
2-Methyltetrahydrofuran (2-MeTHF): A Green Solvent for Pd?NHC-Catalyzed Amide and Ester Suzuki-Miyaura Cross-Coupling by N?C/O?C Cleavage
Lei, Peng,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
supporting information, p. 5654 - 5660 (2019/11/16)
The palladium-NHC-catalyzed (NHC=N-heterocyclic carbene) Suzuki-Miyaura cross-coupling of amides and esters via highly chemoselective N?C(O) and O?C(O) cleavage with aryl boronic acids using green, sustainable and eco-friendly 2-methyltetrahydrofuran (2-MeTHF) is reported. A variety of amides and aryl esters were coupled with aryl boronic acids in high to excellent yields. This method employs commercially-available, air- and moisture-stable Pd(II) ?NHC precatalysts. Crucially, the use of 2-MeTHF leads to the highest TON reported to date in amide N?C(O) bond cross-coupling. This operationally-simple protocol was utilized in the synthesis a bioactive ketone intermediate, emphasizing the potential of 2-MeTHF as a green solvent in unconventional amide bond disconnection. Given the tremendous importance of amide bond cross-coupling strategies and the drive to maintain full sustainability in cross-coupling processes, we expect that the synthetic method will be of broad interest.
Nickel-Catalyzed Molybdenum-Promoted Carbonylative Synthesis of Benzophenones
Peng, Jin-Bao,Wu, Fu-Peng,Li, Da,Qi, Xinxin,Ying, Jun,Wu, Xiao-Feng
, p. 6788 - 6792 (2018/06/04)
A nickel-catalyzed molybdenum-promoted carbonylative coupling reaction for the synthesis of benzophenones from aryl iodides has been developed. Various substituted diaryl ketones were synthesized in moderate to excellent yields under CO-gas-free conditions. A synergetic effect of both nickel and molybdenum has been observed, which is also responsible for the success of this transformation.
Palladium-Catalyzed Carbonylative Homocoupling of Aryl Iodides for the Synthesis of Symmetrical Diaryl Ketones with Formic Acid
Wu, Fu-Peng,Peng, Jin-Bao,Qi, Xinxin,Wu, Xiao-Feng
, p. 173 - 177 (2017/11/27)
A convenient method for the palladium-catalyzed carbonylative homocoupling of aryl iodides was developed. With formic acid as the CO source, various symmetrical diaryl ketones were synthesized in moderate to good yield in the presence of a palladium catalyst.
Suzuki-Miyaura cross-coupling of amides and esters at room temperature: Correlation with barriers to rotation around C-N and C-O bonds
Lei, Peng,Meng, Guangrong,Shi, Shicheng,Ling, Yun,An, Jie,Szostak, Roman,Szostak, Michal
, p. 6525 - 6530 (2017/08/29)
The Suzuki-Miyaura cross-coupling has been widely recognized as one of the most important methods for the construction of C-C bonds. However, in contrast to traditional aryl halide or pseudohalide electrophiles, coupling reactions with unactivated C-N and C-O electrophiles have proven significantly more challenging. Here we report the first general palladium-catalyzed Suzuki-Miyaura cross-coupling of both common amides and aryl esters through the selective cleavage of the C-N and C-O bonds under exceedingly mild conditions. Notably, for the first time we demonstrate selective C(acyl)-N and C(acyl)-O cleavage/cross-coupling under the same reaction conditions. The reaction uses a commercially available, bench-stable and operationally-convenient (η3-1-t-Bu-indenyl)Pd(IPr)(Cl) precatalyst. Furthermore, we demonstrate that the reactivity of generic amides and aryl esters can be correlated with barriers to isomerization around the C(acyl)-X (X = N, O) bond, thus providing a blueprint for the development of a broad range of novel coupling reactions of ester and amide electrophiles by the selective activation of C-O and C-N bonds.
