A new synthetic method is reported in which 2-arylbenz(ox,imid,thi)azoles can be prepared by the palladium catalyzed condensation of aromatic halides with o-amino(phenol, aniline, thiophenol)s followed by dehydrative cyclization. This method is tolerant of a wide variety of functional groups on either aromatic ring and gives good to excellent yields of products.
demonstrated broad substrate scope and good compatibility of functional groups. 2-Aryl benzothiazole and 2-aryl benzoimidazole could be smoothly assembled in the same manner. On the basis of preliminary mechanisticstudies, base initiated and aromatization driven β-carbon elimination was considered to be the key step for the formation of 2. This reaction offers an alternative, facile, and sustainable route to
Pd/Cu-Catalyzed C–H/C–H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
作者:Ze-Yu Tian、Zeng-Hui Lin、Cheng-Pan Zhang
DOI:10.1021/acs.orglett.1c01322
日期:2021.6.4
A highly efficient method for the selective formal C–H/C–H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity
One-Pot Synthesis of 2-Substituted Benzoxazoles Directly from Carboxylic Acids
作者:Dinesh Kumar、Santosh Rudrawar、Asit K. Chakraborti
DOI:10.1071/ch08193
日期:——
Methanesulfonic acid has been found to be a highly effective catalyst for a convenient and one-pot synthesis of 2-substituted benzoxazoles by the reaction of 2-aminophenol with acid chlorides, generated in situ fromcarboxylicacids. Aryl, heteroaryl, and arylalkyl carboxylicacids provided excellent yields of the corresponding benzoxazoles. The reaction conditions were compatible with various substituents
Visible
<scp>Light‐Induced Copper‐Catalyzed</scp>
C—H Arylation of Benzoxazoles
<sup>†</sup>
作者:Xiaodong Ma、Guozhu Zhang
DOI:10.1002/cjoc.201900527
日期:2020.11
copper‐catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron‐poor heterocycles such as thiophene possessing one electron‐withdrawinggroup can also be arylated.