7375-38-4Relevant academic research and scientific papers
NiXantphos: A deprotonatable ligand for room-temperature palladium-catalyzed cross-couplings of aryl chlorides
Zhang, Jiadi,Bellomo, Ana,Trongsiriwat, Nisalak,Jia, Tiezheng,Carroll, Patrick J.,Dreher, Spencer D.,Tudge, Matthew T.,Yin, Haolin,Robinson, Jerome R.,Schelter, Eric J.,Walsh, Patrick J.
supporting information, p. 6276 - 6287 (2014/05/20)
Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd-NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of aryl chloride substrates bearing heteroaryl groups and sensitive functional groups that are known to undergo 1,2-addition, aldol reaction, and O-, N-, enolate-α-, and C(sp2)-H arylations. The advantages and importance of the Pd-NiXantphos catalyst system outlined herein make it a valuable contribution for applications in Pd-catalyzed arylation reactions with aryl chlorides.
Photochemistry and photophysics of (p-benzoylphenyl)diphenylmethyl and (p-benzoylphenyl)bis(4-tert-butylphenyl)methyl radicals in different solvents
Jarikov, Viktor V.,Nikolaitchik, Alexandre V.,Neckers, Douglas C.
, p. 5131 - 5140 (2007/10/03)
The photochemical reactions of (p-benzoylphenyl)diphenylmethyl (1) and (p-benzoylphenyl)bis(4-tert-butylphenyl)methyl (2) in various solvents were investigated. The photophysical parameters of the first excited doublet state of the radicals were measured using spectroscopic and kinetic methods and led to a 'molecular rotor' model to characterize the excited-state behavior. The charge-transfer excited state for both radicals was observed. Photoproducts separated from the photolysis of 1 and 2 in benzene suggest photodecomposition proceeds via H-abstraction (55%), fragmentation (20%), cyclization (10%), and addition (10%).
Superacid-catalyzed reaction of substituted benzaldehydes with benzene
Saito, Shinichi,Ohwada, Tomohiko,Shudo, Koichi
, p. 8089 - 8093 (2007/10/03)
Benzaldehydes bearing an electron-withdrawing group reacted with 2 equiv of benzene in the presence of a superacid, trifluoromethanesulfonic acid, to give substituted triphenylmethane in good yields. On the other hand, benzaldehydes bearing an electron-donating or a neutral group reacted under the similar conditions to give unsubstituted diphenylmethane and triphenylmethanol, together with substituted benzene. We propose a new mechanism of this reaction, which involves transalkylation as the key step.
PHOTOPHYSICS AND PHOTOCHEMISTRY OF P-BENZOYLPHENYLDIPHENYLMETHYL IN SOLUTION
Neckers, D.C.,Rajadurai, S.,Valdes-Aguilera, O.,Zakrzewski, A.,Linden, S.M.
, p. 5109 - 5112 (2007/10/02)
The photochemistry and photophysics of p-benzoylphenyldiphenylmethyl (I) is reported in benzene at room temperature.This report is the first of the photochemical properties of a stable radical conjugated with an n-?* carbonyl group.
Sterically Hindered Free Radicals, XIII. Wittig's Radical 4-Benzoyltriphenylmethyl and Analogous Mono-4-substituted Trityl Radicals
Zarkadis, Antonios K.,Neumann, Wilhelm P.,Uzick, Wolfram
, p. 1183 - 1192 (2007/10/02)
The mono-4-R-triphenylmethyl radicals 1, 8b-f, R = tBu, CF3, COMe, COPh, CN, Me, or their quinonoid dimers 4, 9b-f are prepared, most of them for the first time.The degree of dissociation of the latter at 25 deg C is surprisingly high (=/ 33percent, 0.01 M), donors and acceptors being effective here likewise.ESR data are given and discussed.
LANGLEBIGE α-METALLIERTE METHYLRADIKALE UND DEREN DIMERE
Hillgaertner, Horst,Neumann, Wilhelm P.,Schulten, Winfried,Zarkadis, Antonios K.
, p. 197 - 211 (2007/10/02)
Persistent radicals R'2C-MR3 (I), R'C(MR3)2 (II) and RC(MR3)OMR3 (III), R'=mostly Ph but also t-Bu, H, R'2=also 9-fluorenyl or 9-xanthenyl, M=Si, Ge, Sn, have been generated from the corresponding C-H or C-Hal compounds or by addition of R3M to ketones.Radicals I, II and III are investigated by ESR spectroscopy.A temperature-dependent equilibrium has been found between these radicals and their dimers (IV), of, as far as investigated, quinonoid structure.Dimers IV rearrange with acids giving diaryl methanes.Autoxidation of radicals I at 80 deg C gives thebenzpinacol derivatives, whose radicals are oxidized again, undergoing different fragmentations.At room temperature, however, the dimers IV are attacked by O2 forming the metalated benzophenone derivatives via fragmentation, which are split by UV light into the radicals R3M (M=Si, Ge, Sn) and the oxyl radicals, which are highly stabilised by mesomerism.
