The unexpected conversion of a thiophene ring into a pyrrole ring via a putative nitrene intermediate
作者:Ross W. Harrington、Stephen P. Stanforth
DOI:10.1016/j.tetlet.2012.02.050
日期:2012.4
Triethylphosphite induced reductive cyclisation of 1-(2-nitrophenyl)-3,5-di(2-thienyl)pyrazole 6 afforded the expected 1,3-di(2-thienyl)pyrazolo[1,2-a]benzotriazole 7 (14%) together with an unexpected product which was shown to be a 2-(2-thienyl)pyrazolo[1,5-a]pyrrolo[2,1-c]quinoxaline 8 derivative (27%). A mechanism for the extrusion of sulfur during the transformation of heterocycle 6 into product
亚磷酸三乙酯诱导的1-(2-硝基苯基)-3,5-二(2-噻吩基)吡唑6还原环化反应可提供预期的1,3-二(2-噻吩基)吡唑并[1,2- a ]苯并三唑7(14 %)和意外的产物,该产物显示为2-(2-噻吩基)吡唑并[1,5- a ]吡咯并[ 2,1- c ]喹喔啉8衍生物(27%)。提出了一种在杂环6转化为产物8的过程中挤出硫的机理。