143870-53-5Relevant articles and documents
Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki-Miyaura Reactions of Diarylmethyl Esters
Dardir, Amira H.,Casademont-Reig, Irene,Balcells, David,Ellefsen, Jonathan D.,Espinosa, Matthew R.,Hazari, Nilay,Smith, Nicholas E.
, p. 2332 - 2344 (2021/06/28)
The synthesis of triarylmethanes via Pd-catalyzed Suzuki-Miyaura reactions between diarylmethyl 2,3,4,5,6-pentafluorobenzoates and aryl boronic acids is described. The system operates under mild conditions and has a broad substrate scope, including the coupling of diphenylmethanol derivatives that do not contain extended aromatic substituents. This is significant as these substrates, which result in the types of triarylmethane products that are prevalent in pharmaceuticals, have not previously been compatible with systems for diarylmethyl ester coupling. Furthermore, the reaction can be performed stereospecifically to generate stereoinverted products. On the basis of DFT calculations, it is proposed that the oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrate occurs via an SN2 pathway, which results in the inverted products. Mechanistic studies indicate that oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrates to (IPr)Pd(0) results in the selective cleavage of the O-C(benzyl) bond in part because of a stabilizing η3-interaction between the benzyl ligand and Pd. This is in contrast to previously described Pd-catalyzed Suzuki-Miyaura reactions involving phenyl esters, which involve selective cleavage of the C(acyl)-O bond, because there is no stabilizing η3-interaction. It is anticipated that this fundamental knowledge will aid the development of new catalytic systems, which use esters as electrophiles in cross-coupling reactions.
Modular synthesis of triarylmethanes through palladium-catalyzed sequential arylation of methyl phenyl sulfone
Nambo, Masakazu,Crudden, Cathleen M.
, p. 742 - 746 (2014/01/23)
Triarylmethanes, which are valuable structures in materials, sensing and pharmaceuticals, have been synthesized starting from methyl phenyl sulfone as an inexpensive and readily available template. The three aryl groups were installed through two sequential palladium-catalyzed C-H arylation reactions, followed by an arylative desulfonation. This method provides a new synthetic approach to multisubstituted triarylmethanes using readily available haloarenes and aryl boronic acids, and is also valuable for the preparation of unexplored triarylmethane-based materials and pharmaceuticals. Unsymmetric triarylmethanes have been synthesized starting from methyl phenyl sulfone as an inexpensive and readily available template. The three aryl groups were installed through two sequential palladium-catalyzed C-H arylation reactions, followed by an arylative desulfonation. Copyright
Palladium-catalyzed C(sp3)-H arylation of diarylmethanes at room temperature: Synthesis of triarylmethanes via deprotonative-cross-coupling processes
Zhang, Jiadi,Bellomo, Ana,Creamer, Andrea D.,Dreher, Spencer D.,Walsh, Patrick J.
supporting information; experimental part, p. 13765 - 13772 (2012/10/08)
Although metal-catalyzed direct arylation reactions of non- or weakly acidic C-H bonds have recently received much attention, chemists have relied heavily on substrates with appropriately placed directing groups to steer reactivity. To date, examples of intermolecular arylation of unactivated C(sp3)-H bonds in the absence of a directing group remain scarce. We report herein the first general, high-yielding, and scalable method for palladium-catalyzed C(sp3)-H arylation of simple diarylmethane derivatives with aryl bromides at room temperature. This method facilitates access to a variety of sterically and electronically diverse hetero- and nonheteroaryl-containing triarylmethanes, a class of compounds with various applications and interesting biological activity. Key to the success of this approach is an in situ metalation of the substrate via C-H deprotonation under catalytic cross-coupling conditions, which is referred to as a deprotonative-cross-coupling process (DCCP). Base and catalyst identification were performed by high-throughput experimentation (HTE) and led to a unique base/catalyst combination [KN(SiMe3)2/Pd-NiXantphos] that proved to efficiently promote the room-temperature DCCP of diarylmethanes. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of substrates that are known to undergo O-, N-, enolate-, and C(sp2)-H arylation.
