Synthesis of Substituted Benzenes via Bi(OTf)3-Mediated Intramolecular Carbonyl Allylation of α-Prenyl or α-Geranyl β-Arylketosulfones
摘要:
Intramolecular carbonyl allylation of alpha-prenyl or alpha-geranyl beta-arylketosulfones 5 in the presence of molecule sieves (MS) affords substituted benzenes 6-7 in moderate to good yields. The facile transformation proceeds by a synthetic sequence starting with the alpha-prenylation or alpha-geranylation of 1 and the Bi(OTf)(3)-mediated annulation of 5 followed by a sequential desulfonative aromatization or then an intramolecular FriedelCrafts alkylation. A plausible mechanism has been studied and proposed.
Nickel- or Iron-Catalyzed Cross-Coupling of Aryl Carbamates with Arylsilanes
作者:Wen-Juan Shi、Hong-Wei Zhao、Yang Wang、Zhi-Chao Cao、Li-Sheng Zhang、Da-Gang Yu、Zhang-Jie Shi
DOI:10.1002/adsc.201600590
日期:2016.7.28
Aryl carbamates were for the first time applied as electrophiles in the cross‐coupling with arylsilanes via nickel or iron catalysis to construct valuable biaryl compounds. This new coupling reaction features a good group tolerance and non‐sensitivity to steric hindrance on both aryl carbamates and arylsilanes.
A Cyclobutene-1,2-Bis(imidazolium) Salt as Efficient Precursor of Palladium-Catalyzed Room-Temperature Suzuki-Miyaura Reactions
作者:Andreas Schmidt、Alireza Rahimi
DOI:10.1055/s-0029-1219824
日期:2010.6
3,3′-[3,4-Bis(dichloromethylene)cyclobut-1-ene-1,2-diyl]bis(1-methyl-1 H-imidazolium) bis(tetrafluoroborate),palladium(II)acetate, and sodium TERT-butoxidein toluene catalyze effectively Suzuki-Miyaura cross-couplingreactions of aryl bromides, chlorides, and iodides with arylboronicacids at room temperature.
Amide-Ligand-Controlled Highly <i>para</i>-Selective Arylation of Monosubstituted Simple Arenes with Arylboronic Acids
作者:Yu-Xin Luan、Tao Zhang、Wei-Wei Yao、Ke Lu、Lu-Yao Kong、Yu-Tong Lin、Mengchun Ye
DOI:10.1021/jacs.6b12907
日期:2017.2.8
Pd-catalyzed highly para-selective arylations of monosubstituted simple arenes with arylboronic acids to widely existed biaryls have been developed. Inspired by requisite amide-directing groups in reported selective oxidative couplings, amide ligands, especially DMF, are designed and found to be critical for the selectivity control in current arylations.
273. Studies in the terphenyl series. Part III. The preparation and nitration of m-terphenyl
作者:H. France、I. M. Heilbron、D. H. Hey
DOI:10.1039/jr9390001288
日期:——
Photocatalysis of oligo(p-phenylenes): photoreductive production of hydrogen and ethanol in aqueous triethylamine
Oligo(p-phenylenes) (OPP-n), p-terphenyl (OPP-3) to p-sexiphenyl (OPP-6), catalyze water-reductive H2 formation and reduction of concomitantly formed acetaldehyde to ethanol upon irradiation of heterogeneous suspensions in aqueous organic solution in the presence of triethylamine (TEA) and RuCl3. Colloidal Ru0 is photoformed in situ to work as an electron relay. The activity of OPP-n increases with the number of phenylene units except for the cases of OPP-3 and of the alkylated derivatives, where the net photocatalytic activities are higher, mainly due to the effective homogeneous catalysis, since their solubilities in the solvents employed are significantly larger. The homogeneous photocatalysis of OPP-3 leads not only to H2 evolution but also to effective formation of ethanol in the absence of colloidal Ru0, being accompanied by photo-Birch reduction of OPP-3. Dynamics studies of OPP-3 reveal that photocatalysis should be initiated by formation of the excited singlet state of OPP-3 (1OPP-3*), which is reductively quenched by TEA at a rate controlled by diffusion to produce the OPP-3 radical anion (OPP-3.-) and the TEA radical cation (TEA.+). From laser flash photolysis and pulse radiolysis experiments, it is concluded that electron transfer from OPP-3.- leads to effective reduction of water to H2 catalyzed by Ru0 colloid. Furthermore, it is confirmed that OPP-3.- gives electrons directly to acetaldehyde without any electron relays like colloidal metals, resulting in the formation of ethanol. During photocatalysis, OPP-3 itself undergoes photo-Birch reduction to some extent.