Metal‐Free C−H Borylation of N‐Heteroarenes by Boron Trifluoride

Abstract

Organoboron compounds are essential reagents in modernC ÀCc oupling reactions. Theirs ynthesis via catalytic CÀHb orylation by main group elements is emerging as ap owerful tool alternative to transition metal based catalysis. Herein, as traightforwardm etal-free synthesis of aryldifluoroboranes from BF 3 and heteroarenesisr eported. The reaction is assisted by sterically hindered amines and catalytic amountso ft hioureas. According to computational studies the reaction proceeds via frustrated Lewis pair (FLP) mechanism. The obtained aryldifluoroboranes are further stabilized againstd estructivep rotodeborylation by converting them to the corresponding air stable tetramethylammonium organotrifluoroborates.

Metal-Free ortho-Selective C–H Borylation of 2-Phenylthiopyridines Using BBr3

“…Directed borylation and intermolecular borylation using BX 3 (X = Cl, Br) represent a more powerful way to form C–B bonds. , And an excellent directing group is often crucial for the realization of the electrophilic borylation. As a strongly coordinating group, pyridine is usually used as a directing group or ligand in C–H bonds activation, especially in the direct borylation of arenes .…”

Application of Mutualism in Organic Synthetic Chemistry: Mutually Promoted C−H Functionalization of Indole and Reduction of Quinoline

“…In recent years, the selective functionalization (i. e. borylation or silylation) of C−H bond in N‐ heterocylic aromatics such as indoles has attracted intense attention due to their wide applications in synthesis, [1–3] medicinal chemistry [4,5] and materials sciences [6,7] . Different synthetic strategies have been developed to accomplish this goal by metal [8–23] or metal‐free catalysts [24–35] . Among them, potent boron Lewis acid tris(pentafluorophenyl)borane, B(C 6 F 5 ) 3 , have demonstrated its powerful capability in the C−H borylation (silylation) of indoles [36–39] .…”

Borylation Directed Borylation of Indoles Using Pyrazabole Electrophiles: A One‐Pot Route to C7‐Borylated‐Indolines

“…Electrophilic CÀ H borylation requires a base to facilitate deprotonation of arenium species (via a step-wise or concerted S E Ar mechanism). [20,22,28] The structure of 7-H shows the indoline-N has acted as the Brønsted base and is thus chiral (leading to diasterotopic resonances in 7-H). Thus addition of an exogenous base deprotonates the NÀ H unit of 7-H simplifying 1 H NMR spectra (to two triplets observed for the CH 2 units, Figure S78).…”