Synthesis of 6,6-Difluorocyclopropa[<i>b</i>]furo[2,3-<i>c</i>]pyrrole and 7-Fluorofuro[3,2-<i>c</i>]pyridine Derivatives via 1,5-Electrocyclization of Carbene-Derived Azomethine Ylides
作者:Mikhail Novikov、Igor Voznyi、Alexander Khlebnikov
DOI:10.1055/s-2005-864820
日期:——
Reaction of N-(5-R-furan-2-ylmethylidene)anilines with difluorocarbene, generated in CF 2 Br 2 /Pb*/Bu 4 NBr/ultrasound system proceeds via 1,5-electrocyclization of intermediate azomethine ylides to give 6,6-difluorocyclopropa[b]furo[2,3-c]pyrrol-4(5H)-one or/and 4,4,6,6-tetrafluorocyclopropa[b]furo[2,3-c]pyrrole derivatives. Thermolysis of these compounds under solvent-free conditions gives rise
N-(5-R-呋喃-2-基亚甲基)苯胺与二氟卡宾在CF 2 Br 2 /Pb*/Bu 4 NBr/超声系统中通过中间体偶氮甲碱叶立德的1,5-电环化反应生成6, 6-二氟环丙[b]呋喃[2,3-c]吡咯-4(5H)-一或/和4,4,6,6-四氟环丙[b]呋喃[2,3-c]吡咯衍生物。这些化合物在无溶剂条件下的热解产生高产率的 2,5-二取代 7-氟-4,5-二氢呋喃 [3,2-c] 吡啶-4(5H)-酮。