Dioxopyrrolines. XLIV. Thermal 1,3-shift of 2-azabicyclo(3.2.0)hept-2-ene ring system. A new entry to 3,4-dihydropyridines and 2-azanorborn-2-enes.
作者:Takehiro SANO、Yoshie HORIGUCHI、Kazuhiko TANAKA、Yoshisuke TSUDA
DOI:10.1248/cpb.38.36
日期:——
Thermolysis of 4-oxo-2-azabicyclo[3.2.0]hept-2-enes caused two reactions; one is the 1, 3-shift of the C1-C7 bond to the C3 carbon followed by cheletropic loss of CO from the intermediary formed 2-azanorborn-2-enes to yield the dihydropyridines, and the other is epimerization of the C7-substituent. These two reactions occurred competitively depending on the nature of the C7 substituent. Intermediary formation of the 2-azanorborn-2-enes in the rearrangement reaction was proved by trapping experiments with the use of 4-acetoxy derivatives. The mechanisms of the thermal 1, 3-shift and 7-epimerization are discussed.
4-氧代-2-氮杂双环[3.2.0]庚-2-烯的热解引起两个反应;一种是C1-C7键向C3碳的1, 3-位移,然后从中间形成的2-氮杂降冰片-2-烯中CO的螯合损失,产生二氢吡啶,另一种是C7取代基的差向异构化。这两个反应根据 C7 取代基的性质竞争性发生。通过使用 4-乙酰氧基衍生物的捕获实验证明了重排反应中 2-氮杂降冰片-2-烯的中间形成。讨论了热1、3-位移和7-差向异构化的机制。