18937-93-4Relevant academic research and scientific papers
α-Bromoacrylic Acids as C1 Insertion Units for Palladium-Catalyzed Decarboxylative Synthesis of Diverse Dibenzofulvenes
Zhang, Minghao,Deng, Wenbo,Sun, Mingjie,Zhou, Liwei,Deng, Guobo,Liang, Yun,Yang, Yuan
, p. 5744 - 5749 (2021/08/18)
Herein α-bromoacrylic acids have been employed as C1 insertion units to achieve the palladium-catalyzed [4 + 1] annulation of 2-iodobiphenyls, which provides an efficient platform for the construction of diverse dibenzofulvenes. This protocol enables the formation of double C(aryl)-C(vinyl) bonds via a C(vinyl)-Br bond cleavage and decarboxylation. It is particularly noteworthy that the method features a broad substrate scope, and various interesting frameworks, such as bridged ring, fused (hetero)aromatic ring, and divinylbenzene, can be successfully incorporated into the products.
Atmosphere-Controlled Palladium-Catalyzed Divergent Decarboxylative Cyclization of 2-Iodobiphenyls and α-Oxocarboxylic Acids
Zhou, Liwei,Sun, Mingjie,Zhou, Fengru,Deng, Guobo,Yang, Yuan,Liang, Yun
, p. 7150 - 7155 (2021/09/18)
A novel palladium-catalyzed divergent decarboxylative cyclization of 2-iodobiphenyls and α-oxocarboxylic acids utilizing the atmosphere as a controlled switch is reported. Under the protection of a nitrogen atmosphere, tribenzotropones are synthesized by a [4 + 3] decarboxylative cyclization. Employing a palladium/O2 system enables a [4 + 2] decarboxylative cyclization to assemble triphenylenes. Notably, preliminary mechanistic studies indicate that the formation of triphenylenes involves a double decarboxylation.
Palladium-Catalyzed C-H Amination/[2 + 3] or [2 + 4] Cyclization via C(sp3or sp2)-H Activation
An, Yang,Ding, Ya-Nan,Gou, Xue-Ya,Li, Qiao,Li, Yuke,Liang, Yong-Min,Zhang, Xiao-Yan,Zhang, Zhe
, p. 7961 - 7965 (2021/10/25)
This report describes a palladium-catalyzed Catellani reaction consisting of amination/[2 + 3] or [2 + 4] cyclization via a carboxylate ligand-exchange strategy. This method effectively activates ortho-substituents that avoid a second C-H palladation. The scope of substrates was broad, o-methyl-substituted iodoarenes were applied to the reaction smoothly, and o-phenyl-substituted iodoarenes can also be obtained by this method. In terms of mechanism, density functional theory calculations proved the sequence of the key five-membered aryl-norbornene-palladacycle intermediate formation and C(sp3 or sp2)-H activation.
Photochemical generation and reactivity of naphthyl cations: cine substitution
Slegt, Micha,Minne, Floor,Zuilhof, Han,Overkleeft, Hermen S.,Lodder, Gerrit
, p. 5353 - 5363 (2008/03/14)
The photochemical solvolyses of naphthalen-1-yl(phenyl)-iodonium tetrafluoroborate and naphthalen-2-yl(phenyl)-iodonium tetrafluoroborate in methanol regiospecifically yield the naphthalen-1- and -2-yl ethers but afford scrambled 1- and 2-phenylnaphthalene Friedel-Crafts products. It is demonstrated that singlet naphthyl cations account for the formation of the naphthyl ethers, but that the cine substitution is most likely to be due to the intermediacy of triplet naphthyl cations. According to the experiments reported here, the singlet naphthyl cations are lower in energy than their triplet isomers. High-level MO calculations for the cations in methanol support this finding. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Synthetically Useful Aryl-Aryl Bond Formation via Grignard Generation and Trapping of Arynes. A One Step Synthesis of p-Terphenyl and Unsymmetric Biaryls
Hart, Harold,Harada, Katsumasa,Du, Chi-Jen Frank
, p. 3104 - 3110 (2007/10/02)
A one-pot route to p-terphenyls is described.Addition of 1,4-dibromo-2,5-diiodobenzene, 1, to excess aryl Grignard reagent gives the terphenyl di-Grignard 2 and the trihalo mono-Grignard 5.After aqueous quench, p-terphenyls are isolated in 30percent to 50percent yield (Table I).This yield can be improved to 70-80percent by adding potassium tert-butoxide or lithium tetramethylpiperidide to the reaction mixture prior to workup.Mechanisms involving organometallic aryne intermediates are proposed.With o-bromoiodoarenes in place of tetrahaloarenes the method can be adapted to prepare unsymmetric biaryls in good yield (Table II).
