Mesoionic 1,3-oxazolium-5-olates (münchnones) react with thiocoumarins having an electron-withdrawing group at the 3-position to afford stereodefined fused polycyclic thienopyrroles. The reaction sequence seems to be triggered by a regiospecific dipolar cycloaddition followed by ring opening of the initial 1:1 cycloadduct and intramolecular rearrangement with an unusual ring contraction.
中离子1,3-
恶唑鎓5-酸酯(münchnones)与在3-位具有吸电子基团的
硫香豆素反应,得到立体定义的稠合多环
噻吩并
吡咯。反应顺序似乎是由区域特异性偶极环加成反应引发的,随后是最初的1:1环加合物的开环,以及分子内的重排以及异常的环收缩。