Fuchibe Kohei, Mukohara Ibuki, Yamada Atsushi, Miyazaki Daisuke, Takayama Ryo, Ichikawa Junji
Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
Org Lett. 2022 Jan 14;24(1):169-174. doi: 10.1021/acs.orglett.1c03805. Epub 2021 Dec 12.
The reaction of aryl thiophene-2-carbodithioates or thiophene-3-carbodithioates with difluorocarbene generated from BrCFCOLi/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-]thiophenes or thieno[2,3-]thiophenes. The reactions of the oxygen analogues, aryl furancarbodithioates, also proceeded to afford the corresponding thieno[3,2-]furans. Intramolecular fluorine substitution in the produced arylsulfanyl(fluoro)thienofurans allowed for another thiophene ring construction, leading to the synthesis of fused pentacyclic thienothienofurans.
