臺灣博碩士論文加值系統

　　Dimethyl-3,3-cyclopentyl-3H-pyrazole-4,5-dicarboxylate(20)受熱後產生 dimethyl-1,5-tetramethylene-pyrazole-3,4-dicarboxylate(25,8%), dimethyl-4,5,6,7-tetrahydroindazole-2,5-dicarboxylate (24,69%)，methyl-4,5,6,7-tetrahydroindazole-5-carboxylate (26,6%)，其反應機構被解釋為可能有二種競爭路徑(1)化合物 20 之 C3 位的cyclopentyl group 會依逆時針方向擴環遷移至N2位上進行所謂 1,5-sigmatropic migration，而生成化合物25，(2)反之，另一途徑為上述之 cyclopentyl group 會先依順時針方向擴環遷移至C4位上進行1,5-migration，接C4位上之 ester group再依逆時針方向遷移至N2位上，生成化合物24。接著化合物24在 N2位上的 ester group會在高溫下脫去而形成化合物26。化合物20 在四種不同的溫度下之加熱反應，其活化能 Ea=8.60 kcal/mole.k。

　　Thermolysis of dimethy1-3,3-cyclopentyl-3H-pyrazole-4,5-dicarboxylate(20) afforded dimethy1-4,5,6,7-tetrahydroindazole-2,5-dicarboxylate(24) and dimethy1-1,5-tetramethylene-pyrazole-3,4-dicarboxylate(25) in 69% and 8%, respectively. The mechanism of this reaction is suggested to undergo two competitive pathways. (1)After heating the compound 20 can undergo ring expansion(1,5-sigmatropic migration), i.e. the cyclopentyl group can ring-expand form C3 to N2 to form the compound. 25. (2) Alternatively, the cyclopentyl group of the compound 20 can undergo ring expansion from C3 to C4, and the ester group at C4 can simultaneously migrate to N2(1,5-anticlockwise) to form the compound 24. The activation energy of the thermal reaction of compound 20 was measured be 8.6kcal/mole.k