19256-46-3Relevant academic research and scientific papers
Palladium-Assisted "Aromatic Metamorphosis" of Dibenzothiophenes into Triphenylenes
Vasu, Dhananjayan,Yorimitsu, Hideki,Osuka, Atsuhiro
, p. 7162 - 7166 (2015)
Abstract Two new palladium-catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4-chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium-catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular SN2 reaction to form a teraryl sulfonium salt, and 4) palladium-catalyzed intramolecular C-S/C-H coupling through electrophilic palladation. Symmetrical as well as unsymmetrical triphenylenes of interest were synthesized in a tailor-made fashion in satisfactory overall yields. A change of heart: The invention of two palladium-catalyzed arylation reactions of organosulfur compounds enabled the transformation of dibenzothiophenes into triphenylenes and thus a fundamental change in the core aromatic structure (see scheme). Both symmetrical and unsymmetrical triphenylenes were synthesized in a tailor-made fashion in satisfactory overall yield.
Metal-Free sp2-C-H Borylation as a Common Reactivity Pattern of Frustrated 2-Aminophenylboranes
Chernichenko, Konstantin,Lindqvist, Markus,Kótai, Bianka,Nieger, Martin,Sorochkina, Kristina,Pápai, Imre,Repo, Timo
supporting information, p. 4860 - 4868 (2016/05/10)
C-H borylation is a powerful and atom-efficient method for converting affordable and abundant chemicals into versatile organic reagents used in the production of fine chemicals and functional materials. Herein we report a facile C-H borylation of aromatic and olefinic C-H bonds with 2-aminophenylboranes. Computational and experimental studies reveal that the metal-free C-H insertion proceeds via a frustrated Lewis pair mechanism involving heterolytic splitting of the C-H bond by cooperative action of the amine and boryl groups. The adapted geometry of the reactive B and N centers results in an unprecedentently low kinetic barrier for both insertion into the sp2-C-H bond and intramolecular protonation of the sp2-C-B bond in 2-ammoniophenyl(aryl)- or -(alkenyl)borates. This common reactivity pattern serves as a platform for various catalytic reactions such as C-H borylation and hydrogenation of alkynes. In particular, we demonstrate that simple 2-aminopyridinium salts efficiently catalyze the C-H borylation of hetarenes with catecholborane. This reaction is presumably mediated by a borenium species isoelectronic to 2-aminophenylboranes.
Regioselective Dihydroarene Oxide Formation during ortho-Hydroxylation of Halogenobenzenes by Fungi
Auret, Barbara J.,Balani, Suresh K.,Boyd, Derek R.,Greene, Ruth M. E.,Berchtold, Glenn A.
, p. 2659 - 2664 (2007/10/02)
ortho-Hydroxylation of chloro- and bromo-benzene occurred in the presence of growing cultures of the fungi Rhizopus arrhizus, Rhizopus stolonifer, and Cunninghamella elegans.The absence of a primary kinetic isotope effect and the presence of the NIH shift are consistent with dihydroarene oxides being initial metabolites.N.m.r. analysis of the deuterium-labelled o-halogenophenol products suggested that enzyme-catalysed epoxidation occurs preferentially at the 2,3-bond.
