Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents
作者:Carlos Vila、Massimo Giannerini、Valentín Hornillos、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1039/c3sc53047g
日期:——
Palladium-catalysed cross-coupling of secondary C(sp3) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C–C bond formation with organolithium reagents, herein we present a Pd-catalysed cross-coupling of secondary alkyllithium reagents with aryl and alkenyl bromides. The reaction proceeds at room temperature and on short timescales with high selectivity and yields. This methodology is also applicable to hindered aryl bromides, which are a major challenge in the field of metal catalysed cross-coupling reactions.
Radical Ion Probes. 9. The Chemistry of Radical Cations Derived from 9-Cyclopropylanthracene and 9-Bromo-10-cyclopropylanthracene
作者:Yonghui Wang、Karen H. McLean、J. M. Tanko
DOI:10.1021/jo971524t
日期:1998.2.1
Reactions of radical cations generated from 9-cyclopropylanthracene (1) and 9-bromo-10-cyclopropylanthracene (2) in the presence of methanol have been investigated electrochemically. The major products arising from oxidation of both substrates are attributable to CH(3)OH attack at the aromatic ring (occurring at the radical cation stage for 2 and the dication stage for 1) rather than CH(3)OH-induced
Direct Suzuki‐Miyaura Coupling of Naphthalene‐1,8‐diaminato (dan)‐Substituted Cyclopropylboron Compounds
作者:Mikinao Koishi、Kazuki Tomota、Masaaki Nakamoto、Hiroto Yoshida
DOI:10.1002/adsc.202201141
日期:2023.3.7
describe the direct Suzuki-Miyaura coupling of dan-substituted, saturated organoboroncompounds. Despite its Lewis acidity-diminished character of the boron center, cyclopropyl-B(dan) can be activated by t-BuOK to undergo transmetalation with a palladium complex. The increased s-character of the C−B(dan) bond as compared with other alkyl-B(dan) should be the key to the reaction.
Conformational analysis of cyclopropyl groups attached to trigonal carbon in organic radicals
作者:Nathan L. Bauld、John D. McDermed、Charles E. Hudson、Yong S. Rim、Jerome Zoeller、Ronnie Drew Gordon、James S. Hyde
DOI:10.1021/ja01052a023
日期:1969.11
Kinetic vs. thermodynamic factors in .alpha.-hydrogen atom abstractions from alkylaromatics. 2. Reactivities of .alpha.-alkylnaphthalenes and several conformationally locked alkylaromatics toward bromine atom
作者:James M. Tanko、N. Kamrudin、Joseph F. Blackert
DOI:10.1021/jo00022a034
日期:1991.10
The relative reactivities of alpha-methyl-, alpha-ethyl-, and alpha-isopropylnaphthalene toward bromine atom have been determined. A partial breakdown in the normal reactivity pattern (tertiary > secondary > primary) is observed: CH3 (1.00) < CH2CH3 (5.7) > CH(CH3)2 (4.7) per hydrogen at 80-degrees-C. These data (in conjunction with earlier results for the phenyl and 9-anthryl series) show that for alkylaromatics in general, the anticipated correlation between log (k(rel)) and DELTA-H-degree for alpha-hydrogen abstractions by bromine atom is poor. This breakdown in the Evans and Polanyi (E&P) relationship and the observed selectivity reversals in the alpha-naphthyl and 9-anthryl series are attributed to stereoelectronic factors, specifically the alignment of the alpha-C-H bond with the adjacent pi-system in the starting alkylaromatic. The reactivities of indane, 1,8-ethylenenaphthalene, and 1,9-ethyleneanthracene (relative to the corresponding ethylarenes) provide further evidence for the role of stereoelectronic factors. These stereoelectronic factors are reconciled with the E&P equation quantitatively: An excellent correlation between log k(rel) and (sin2 theta x DELTA-H-degree is observed (where theta is the angle defined by the alpha-C-H bond with respect to the aromatic plane). The basis for this treatment and its relationship to the E&P equation is discussed.