Construction of Thienothiophene and Thienofuran Ring Systems via Ring Expansion of Difluorothiiranes Generated from Dithioesters
作者:Kohei Fuchibe、Ibuki Mukohara、Atsushi Yamada、Daisuke Miyazaki、Ryo Takayama、Junji Ichikawa
DOI:10.1021/acs.orglett.1c03805
日期:2022.1.14
The reaction of aryl thiophene-2-carbodithioates or thiophene-3-carbodithioates with difluorocarbene generated from BrCF2CO2Li/molecular sieves 4A produced arylsulfanylated 2,2-difluoro-3-thienylthiiranes. In the presence of lithium ion, the thiirane intermediates underwent ring expansion followed by HF elimination, leading to fluorinated thieno[3,2-b]thiophenes or thieno[2,3-b]thiophenes. The reactions
芳基噻吩-2-碳二硫酸酯或噻吩-3-二硫代碳酸酯与由 BrCF 2 CO 2 Li/分子筛 4A 生成的二氟卡宾反应产生芳基硫烷基化 2,2-二氟-3-噻吩基硫杂环丙烷。在锂离子存在的情况下,硫杂丙环中间体经历扩环然后消除HF,产生氟化噻吩并[3,2- b ]噻吩或噻吩并[2,3- b ]噻吩。氧类似物芳基呋喃碳二硫酸酯的反应也进行得到相应的噻吩并[3,2- b]呋喃。生成的芳基硫烷基(氟)噻吩并呋喃中的分子内氟取代允许构建另一个噻吩环,从而合成稠合的五环噻吩并呋喃。