A highly efficient TBAF-promoted intramolecular cyclization of gem-dibromoolefins for the synthesis of 2-bromobenzofurans(thiophenes)
作者:Wei Chen、Yicheng Zhang、Lei Zhang、Min Wang、Lei Wang
DOI:10.1039/c1cc13967c
日期:——
A highlyefficient tetra-(n-butyl)ammonium fluoride (TBAF)-promoted intramolecular cyclization of gem-dibromoolefins has been developed for the synthesis of 2-bromobenzofused heterocycles. The reaction provides a convenient approach to 2-bromobenzofurans(thiophenes) from the corresponding readily available gem-dibromovinyl substrates without a metal.
Intramolecular cross-coupling of gem-dibromoolefins: a mild approach to 2-bromo benzofused heterocycles
作者:Stephen G. Newman、Valentina Aureggi、Christopher S. Bryan、Mark Lautens
DOI:10.1039/b912093a
日期:——
Highly useful halogenated benzofurans and benzothiophenes are prepared from readily available gem-dibromoolefins using a mild, ligand-free copper catalyzed cross-coupling procedure.
Bromide as the Directing Group for β-Arylation of Thiophenes
作者:Hong-Hai Zhang、Cai-Xia Wang、Fei-Fei Sheng、Kai-Hui Liu、Jian-Guo Gu、Kang Shen、Zheng-Yi Sun、Kunlun Hong
DOI:10.1055/a-1838-8958
日期:2022.9
Direct β-arylation of thiophene derivatives with bromide as directing group is disclosed. The reaction is conducted with PdCl2/(p-tolyl)3P as catalyst, silver carbonate as additive, and aryl iodide as coupling partner, affording brominated biaryl compounds as product. Control experiments indicated that the presence of bromide group enhances the reactivity of the C–H bond, enabling β-arylation. Furthermore
Trace amount Cu (ppm)-catalyzed intramolecular cyclization of 2-(gem-dibromovinyl)phenols(thiophenols) to 2-bromobenzofurans(thiophenes)
作者:Yong Ji、Pinhua Li、Xiuli Zhang、Lei Wang
DOI:10.1039/c3ob40531a
日期:——
An intramolecular cyclization of 2-(gem-dibromovinyl)phenols(thiophenols) to give 2-bromobenzofurans(thiophenes) in the presence of a trace amount of Cu (0.0064 mol%, 25 ppm) has been developed. The reaction provides the desired products in excellent yields under fluoride-free and mild reaction conditions and with a TON (turnover number) of up to 1.5 × 104.