The metal-free thermal organocatalytic pinacolcoupling of arylaldehydes has been developed. The intermolecular coupling of arylaldehydes catalyzed by t-butyl isonicotinate with bis(pinacolato)diboron as the co-reducing agent afforded 1,2-diphenylethane-1,2-diols. This reaction was also applicable to the intramolecular coupling of 1,1′-biphenyl-2,2′-dicarbaldehydes to afford 9,10-dihydrophenanthrene-9
作者:Jaya S. Kudavalli、Derek R. Boyd、Dara Coyne、James R. Keeffe、David A. Lawlor、Aoife C. MacCormac、Rory A. More O’Ferrall、S. Nagaraja Rao、Narain D. Sharma
DOI:10.1021/ol1014027
日期:2010.12.3
initial conformations, one of which is stabilized by hyperconjugation amplified by an aromatic no-bond resonance structure (HOC6H6+ ↔ HOC6H5 H+). MP2 calculations and an unfavorable effect of benzoannelation on benzeniumion stability, implied by pKR measurements of −2.3, −8.0, and −11.9 for benzenium, 1-naphthalenium, and 9-phenanthrenium ions, respectively, support the explanation.
苯-顺-和反-1,2-二氢二醇以显着不同的速率经历酸催化脱水:k cis / k trans = 4500。这可以通过形成不同初始构象的β-羟基碳正离子中间体来解释,其中之一是通过芳香族无键共振结构(HOC 6 H 6 + ↔ HOC 6 H 5 H +)放大的超共轭稳定。MP2 计算和苯并退火对苯离子稳定性的不利影响,由 p K R暗示对苯、1-萘和 9-菲离子分别测量的 -2.3、-8.0 和 -11.9 支持了这一解释。
Hyperaromatic Stabilization of Arenium Ions: A Remarkable <i>Cis</i> Stereoselectivity of Nucleophilic Trapping of <b>β</b>-Hydroxyarenium Ions by Water
作者:David A. Lawlor、Jaya Satyanarayana Kudavalli、Aoife C. MacCormac、Dara A. Coyne、Derek R. Boyd、Rory A. More O’Ferrall
DOI:10.1021/ja207160z
日期:2011.12.14
from enhanced conjugation arising from the stabilizing influence of an aromatic ring in the no-bond resonance structures representing the hyperconjugation (C(6)H(6)OH(+) ↔ C(6)H(5)OH H(+)). This is consistent with an earlier suggestion by Mulliken and a demonstration by Schleyer that the benzenium ion is subject to hyperconjugative aromatic stabilization. It is proposed that, in analogy with the terms
A Novel Nickel(0)-Catalyzed Cascade Ullmann-Pinacol Coupling: From <i>o</i>-Bromobenzaldehyde to <i>trans</i>-9,10-Dihydroxy-9,10-dihydrophenanthrene
作者:Tian-pa You、Shuang-zheng Lin、Qing-an Chen
DOI:10.1055/s-2007-984543
日期:——
Using 5 mol% of (Ph3P)2NiCl2 as a catalyst, Zn powder as a reductant, ortho-carbonyl-substituted aryl halides could be coupled to form trans-9,10-dihydroxy-9,10-dihydrophenanthrenes in a one-pot cascade reaction.
Reactions of K-region oxides of carcinogenic and noncarcinogenic aromatic hydrocarbons. Comparative studies on reactions with nucleophiles and acid-catalyzed reactions.
Several K-region arene oxides of carcinogenic and noncarcinogenic polycyclic aromatic hydrocarbons were synthesized, and their reactivities with various nucleophiles and their acid-catalyzed reactions were discussed. Relationship between these chemical reactivities and mutagenicity was also discussed.
合成了几种致癌和非致癌多环芳烃的 K 区芳烃氧化物,并讨论了它们与各种亲核物的反应活性及其酸催化反应。还讨论了这些化学反应性与致突变性之间的关系。