Palladium-catalyzed ortho-nitration of 2-arylbenzoxazoles
摘要:
An efficient and general protocol for palladium-catalyzed chelation-assisted ortho-nitration of 2-arylbenzoxazoles has been developed. This nitration exhibits high regioselectivity for the substrates, and the reaction could tolerate many functional groups such as F, Cl, Br, CH3, CH3O, affording ortho-nitration products in moderate to good yields. Moreover, some 2-arylbenzoxazole heterocyclic analogues proceed well under this catalytic system. Further studies have been performed to obtain insight into the mechanism. (C) 2015 Elsevier Ltd. All rights reserved.
Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: enhancement of the reaction rate and selectivity by a base
作者:Lin Wang、Zhi-Gang Ma、Xiao-Jing Wei、Qing-Yuan Meng、Deng-Tao Yang、Shao-Fu Du、Zi-Fei Chen、Li-Zhu Wu、Qiang Liu
DOI:10.1039/c4gc00337c
日期:——
An efficient visible-light-driven photocatalytic oxidation of various 2-substituted dihydropyrimidines and phenolic imines has been achieved using an organic photocatalyst eosin Y bis(tetrabutyl ammonium salt) (TBA-eosin Y) and inexpensive oxidant molecular oxygen. With the aid of a base, significantly enhanced photoinduced electron transfer from substrates dihydropyrimidines or phenolic imines to the excited state of TBA-eosin Y has enabled the aerobic oxidation to yield 2-(methylthio)pyrimidines or 2-arylbenzoxazoles selectively.
Mixed N-heterocycles/N-heterocyclic carbene palladium(II) allyl complexes as precatalysts for direct arylation of azoles with aryl bromides
作者:Jin Yang
DOI:10.1016/j.tet.2019.02.031
日期:2019.4
A series of mixed N-heterocycles/N-heterocyclic carbene palladium(II) allylcomplexes with general formula [(NHC)Pd(η3-allyl)]2(μ2-N-heterocycles)(BF4)2 were prepared in one pot based on anion metathesis of (NHC)Pd(η3-allyl)Cl complexes and then ligand replacement with N-heterocycles [N-heterocycles = pyrazine (pyz), 4,4′-bipyridine (bpy) and trans-4,4′-bipyridylethylene (bpe)]. The solid-state structures
Palladium-Catalyzed Intra- and Intermolecular C–H Arylation Using Mesylates: Synthetic Scope and Mechanistic Studies
作者:Devin M. Ferguson、Stacey R. Rudolph、Dipannita Kalyani
DOI:10.1021/cs500587b
日期:2014.7.3
This paper describes the development of Pd-catalyzed inter- and intramolecular direct arylation using mesylates. Furthermore, a sequential mesylation/arylation protocol using phenols as substrates is described. These transformations are general with respect to the electronics of the C-H substrates and allow for the synthesis of diverse heterocyclic motifs in good yields. Both arenes and heteroarenes
We report herein a two‐step one‐pot strategy for the synthesis of benzoxazoles from amides by using cesium fluoride/copper as catalysts. This approach involves the in situ generation of acyl fluorides from the corresponding amides, and the acyl fluorides undergo transamidation and cyclization to give benzoxazoles in good yields. In this work, the amide C−N bonds are activated by CsF to form the acyl