77421-13-7Relevant articles and documents
Para-Selective C-H Borylation of Common Arene Building Blocks Enabled by Ion-Pairing with a Bulky Countercation
Mihai, Madalina T.,Williams, Benjamin D.,Phipps, Robert J.
, p. 15477 - 15482 (2019/10/11)
The selective functionalization of C-H bonds at the arene para position is highly challenging using transition metal catalysis. Iridium-catalyzed borylation has emerged as a leading technique for arene functionalization, but there are only a handful of strategies for para-selective borylation, which operate on specific substrate classes and use bespoke ligands or catalysts. We describe a remarkably general protocol which results in para-selectivity on some of the most common arene building blocks (anilines, benzylamines, phenols, benzyl alcohols) and uses standard borylation ligands. Our strategy hinges upon the facile conversion of the substrates into sulfate or sulfamate salts, wherein the anionic arene component is paired with a tetrabutylammonium cation. We hypothesize that the bulk of this cation disfavors meta-C-H borylation, thereby promoting the challenging para-selective reaction.
Rhodium-Catalyzed meta-C?H Functionalization of Arenes
Bera, Milan,Agasti, Soumitra,Chowdhury, Rajdip,Mondal, Rahul,Pal, Debasis,Maiti, Debabrata
supporting information, p. 5272 - 5276 (2017/04/27)
Rhodium-catalyzed ortho-C?H functionalization is well known in the literature. Described herein is the Xphos-supported rhodium catalysis of meta-C?H olefination of benzylsulfonic acid and phenyl acetic acid frameworks with the assistance of a para-methoxy-substituted cyano phenol as the directing group. Complete mono-selectivity is observed for both scaffolds. A wide range of olefins and functional groups attached to arene are tolerated in this protocol.
Palladium(II)-Catalyzed meta-C-H Olefination: Constructing Multisubstituted Arenes through Homo-Diolefination and Sequential Hetero-Diolefination
Bera, Milan,Maji, Arun,Sahoo, Santosh K.,Maiti, Debabrata
supporting information, p. 8515 - 8519 (2015/11/27)
Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium-catalyzed synthesis of divinylbenzenes by meta-C-H olefination of sulfone-based arenes. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5-trialkenylated compounds can be generated upon successful removal of the directing group. Jockeying for position: Reported herein is the palladium-catalyzed synthesis of mono- and divinylbenzenes by meta-C-H olefination of benzyl sulfones. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. DG=directing group.