183313-50-0Relevant academic research and scientific papers
Efficient cross-coupling of aryl chlorides with arylzinc reagents catalyzed by amido pincer complexes of nickel
Wang, Li,Wang, Zhong-Xia
, p. 4335 - 4338 (2007)
The nickel-catalyzed Negishi cross-coupling reaction of aryl chlorides with arylzinc compounds was investigated. The nickel complexes with the amido pincer type of ligands exhibited high catalytic activity and good functional group tolerance.
Intramolecular reactivity of arylcarbenes: Biphenyl-2-ylcarbenes
Dorra, Michael,Gomann, Klaus,Guth, Michael,Kirmse, Wolfgang
, p. 598 - 610 (2007/10/03)
Biphenyl-2-ylcarbenes, 2-ArC6H4CR, were generated photolytically and thermally from diazo precursors. Cyclization, leading to fluorenes, competes with capture of the carbenes by methanol but proceeds faster than intramolecular hydrogen shifts (with R = Me) and intermodular C - H insertion reactions (with R = H in cyclohexane). By comparison of product ratios with kinetic data for related carbenes from the literature, the cyclization rate is estimated as ca 1011 s-1. The intramolecular reactivity of biphenyl-2-ylcarbenes is not significantly attenuated by variation of R (R = H, Me, Ph). Very minor effects of triplet sensitization and methanol quenching indicate that fluorenes arise from spin-equilibrated biphenyl-2-ylcarbenes, presumably from the singlet state. When Ar = mesityl, the carbene predominantly inserts into C - H bonds of the 2′-methyl groups, giving rise to a dihydrophenanthrene. Formation of a fluorene derivative, by formal insertion into C - C bonds, occurs as a minor process. This unprecedented reaction points to intervention of an o-xylylene in which the methyl group migrates. Laser flash photolysis (LFP) of 2-PhC6H4CN2Ph generates a transient absorption which is due to the T0→Tn transition of 9-phenylfluorene rather than to the presumed o-xylylene. On LFP of 2-ArC6H4CN2Ph in trifluoroethanol-acetonitrile, protonation of the carbenes gives rise to carbocations, 2-ArC6H4CH+Ph. The transient absorption spectra of these cations are strongly influenced by twisting about the Ar - Ar bond (Ar = Ph 4.
