Pyrimidine-directed metal-free C–H borylation of 2-pyrimidylanilines: a useful process for tetra-coordinated triarylborane synthesis

Abstract

Convenient, easily handled, laboratory friendly, robust approaches to afford synthetically important organoboron compounds are currently of great interest to researchers. Among the various available strategies, a metal-free approach would be...

Regioselective Transition‐Metal‐Free Arene C−H Borylations: From Directing Groups to Borylation Template Reagents

“…Functionalized anilines 4 bearing a non‐removable pyrimidine directing group were also reported to undergo efficient metal free C−H borylation in the ortho ‐position under mild conditions within short reactions time to provide borylated amines 6 (Scheme 1b) [4] . More recently, alkyl and aryl phosphine substituents were used as P‐directing groups for the transition‐metal‐free borylation of naphthyl and biaryl phosphines such as 7 (Scheme 1c), providing a straightforward access to pinacolboronates, organotrifluoroborates, and other borylated derivatives 8 – 9 [5]…”

“…[3] Functionalized anilines 4 bearing a non-removable pyrimidine directing group were also reported to undergo efficient metal free CÀ H borylation in the ortho-position under mild conditions within short reactions time to provide borylated amines 6 (Scheme 1b). [4] More recently, alkyl and aryl phosphine substituents were used as P-directing groups for the transition-metal-free borylation of naphthyl and biaryl phosphines such as 7 (Scheme 1c), providing a straightforward access to pinacolboronates, organotrifluoroborates, and other borylated derivatives 8-9. [5] The bicyclic and tricyclic borylated intermediates 2, 5, and 8 (Scheme 1) were characterized by NMR spectroscopy, and the CÀ H borylations occurred via a five or six membered ring through an intramolecular electrophilic aromatic substitution and cyclization on a [L-BBr 2 ] + (L = N or P) borenium ion intermediate.…”

Polymers based on thieno[3,4-c]pyrrole-4,6-dione and pyromellitic diimide by CH–CH arylation reaction for high-performance thin-film transistors

“…23–25 Very recently, transition metal-free oxidation acylation of arenes has shown a promising method for oxidative acylation of different heteroarenes. 26,27 Oxidative coupling of C–H bonds without prior functionalization is an environmentally friendly, step-economically, and sustainable method. 28–30…”

“…[23][24][25] Very recently, transition metal-free oxidation acylation of arenes has shown a promising method for oxidative acylation of different heteroarenes. 26,27 Oxidative coupling of C-H bonds without prior functionalization is an environmentally friendly, step-economically, and sustainable method. [28][29][30] During the last decade, the performance of organic thin-lm transistors (OTFT) has advanced dramatically with the charge carrier mobility (m) and now approaching 100 cm 2 V −1 s −1 .…”

Metal-Free Boron-Mediated ortho-C–H Hydroxylation of N-Benzyl-3,4,5-tribromopyrazoles

“…However, the harsh reaction conditions were necessary. At present, the most attractive strategy to construct C–B bonds would involve the use of boron trihalide (especially BBr 3 ) with a directing group (DG), such as acyl, pyridines, imidazolones, pyrazines, pyrimidines, imidazoles , and imine . In 2020, Shi and co-workers reported the boron-mediated directed aromatic (anilines and indoles) C–H hydroxylation for preparing phenols (Scheme b).…”