21221-91-0Relevant articles and documents
(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.
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.
Method for preparing symmetric diarylketone through catalytic oxidative carbonylation
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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).
