Ru-Catalyzed ortho-Selective Diborylation of 2-Arylpyridines toward the Construction of π-Conjugated Functions

Abstract

A ruthenium catalytic ortho-C–H diborylation of 2-arylpyridine derivatives, including challenging 2-phenoxypyridine functions, using a remarkably low catalyst loading and a low-cost and bench-stable boron source, has been developed. The novel strategy shows high activity with excellent selectivity and may offer a versatile and green alternative to currently employed high loadings of noble metals or extra additives for the selective borylations.

Combined KOH/BEt3 Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores

“…In contrast, BEt 3 is more air-stable and at least 100 times less expensive than B­(C 6 F 5 ) 3 . Inspired by previous works, , we herein report KOH/BEt 3 -catalyzed hydrogenolysis of C–N bonds in acyl-iminodibenzyl derivatives to produce iminodibenzyl luminophores in good yield and high selectivity (Scheme c), high Lewis acid strength, and low environmental impact, and significant progress has been made in recent years. Notably, since the ground-breaking finding that the strong boron Lewis acid B­(C 6 F 5 ) 3 can activate Si–H bonds through η 1 -coordination, this Lewis acid has emerged as a powerful tool for cleavage of carbon–heteroatom bonds .…”

“…In contrast, BEt 3 is more air-stable and at least 100 times less expensive than B­(C 6 F 5 ) 3 . Inspired by previous works, , we herein report KOH/BEt 3 -catalyzed hydrogenolysis of C–N bonds in acyl-iminodibenzyl derivatives to produce iminodibenzyl luminophores in good yield and high selectivity (Scheme c). 3-Chloro-iminodibenzyl ( 2a ) is an important precursor for the construction of highly valuable Clomipramine, which is used as a treatment for depression.…”

Metal-catalysed C–H bond activation and borylation

“…Recently, the Yang group developed 152 a method for the ortho , ortho ′-diborylation of 2-arylpyridine derivatives using a ruthenium catalyst with a low catalyst loading (0.5 mol%) at 120 °C (Scheme 47). Using 2.5 equiv.…”