本論文主要在討論有關於給電子基不對稱單取代之6-(1’,1’-diethylmethyl)fulvene (2n) 和8,8-dicyanoheptafulvene (8a) 加熱進行分子間 [m+n] 環化加成反應研究;對其進行環化加成反應相互之間的反應性、立體選擇性 (Diastereoselectivity)、位置選擇性 (Periselectivity) 和位向選擇性 (Regioselectivity),有進一步徹底而詳細的研究探討。
實驗結果顯示,在60℃CHCl3迴流的高溫反應條件下,8,8-dicyanoheptafulvene (8a)和給電子基不對稱單取代之6-(1’,1’-diethylmethyl)fulvene (2n)反應,則會顯示出百分之百之 endo立體選擇性和位向選擇性與不錯之位置選擇性,進行﹝4+2﹞環化加成反應得到同向(syn)-endo-〔4+2〕環化加成生成物 20n/20n’,比例約為2:1;或是進行﹝4+2﹞環化加成反應得到反向(anti)-endo-〔4+2〕環化加成生成物 21n/21n’,比例約為1:2。
The investigation of this research involves the synthesis and intermolecular [m+n] cycloadditions of the unsymmetrically electron-rich 6-monosubstituted 6-(1’,1’-diethylmethyl)fulvene (2n) with 8,8-dicyanoheptafulvene (8a);designed to establish the experimental analyses of the reactivity, diastereoselectivity, periselectivity, and regioselectivity of these cycloadditions.
The cycloaddition reaction of 8,8-dicyanoheptafulvene (8a) with 6-(1’,1’-diethylmethyl)fulvene (2n) at 60℃ temperature gave the syn-endo-[4+2] cycloadducts 20n/20n’ in a ratio of about 2:1 and the anti-endo-[4+2] cycloadducts 21n/21n’ in a ratio of about 1:2. The present results show that these [4+2] cycloaddition reactions took place with exclusive endo diastereoselectivity and regioselectivity. Good periselectivity was also observed.