Thermal rearrangement of spiro[naphthalene(naphthopyranofurazan)]oxides to spiro[naphthalene(phenalenofurazan)oxides. A probable furazan oxide triggered tandem isomerisation process
作者:Paraskevi Supsana、Theodoros Liaskopoulos、Stavroula Skoulika、Antonios Kolocouris、Petros G. Tsoungas、George Varvounis
DOI:10.1016/j.tet.2005.03.068
日期:2005.6
Thermal rearrangement of (±)-spironaphthalene-1(2H),4′-(naphtho-[2′,1′:2,3]pyrano[4,5-c]furazan)}-2-one-11′-oxides in DMF or acetic anhydride at 140 °C gave an isomeric mixture of (±)-spironaphthalene-1(2H),1′-(5′-hydroxyphenalene[1,2-c]furazan)}-2-one-2′-oxides and 4′-oxides. The rearranged structure was confirmed from X-ray analysis and was consistent with the through space NOE data. The rearrangement
(±)-螺萘-1(2 H),4'-(萘-[2',1':2,3]吡喃并[4,5- c ]呋喃山)}-2-one-的热重排在140°C下于DMF或乙酸酐中形成11'-氧化物,生成(±)-螺萘-1(2 H),1'-(5'-羟基苯并[1,2- c ]呋喃山)}的异构体混合物-2-one-2'-氧化物和4'-氧化物。通过X射线分析证实了重排的结构,并且该结构与穿越空间的NOE数据一致。建议重排是整体串联异构化过程。使用可变温度1 H NMR光谱,一对互变异构体的异构化屏障的下限经计算为22 kcal mol -1在423 K下通过可变温度1 H NMR研究了一对异构体的异构化平衡。异构化势垒的下限经计算为在423 K下为22 kcal mol -1。该低值可表明通过色谱法分离异构体时遇到的困难。半经验AM1和分子力学计算表明,(±)-螺萘-1(2 H),1'-(5'-羟基苯[1,2- c]根据