The reaction mechanism study of 2,2'-di(phenylethynyl)-4,4'-disubstituted-biphenyls cyclization reaction

2,2’-雙(苯乙烯基)-聯苯，在高溫下會進行分子內的關環反應，得到化合物6。為了確認反應機制是經由何種中間體，我們合成了一系列的2,2’-雙(苯乙烯基)-4,4’-雙取代聯苯，嘗試以四苯基環戊二烯酮，捕捉benzocyclobutadiene類型的反應中間體。我們成功地得到此中間體與四苯基環戊二烯酮進行加成反應的產物化合物7。因此我們認為反應是經由benzocyclobutadiene類型的中間體，而非diradical類型的中間體。但也無法完全排除經由diradical 途徑的可能性。另外，我們也探討4,4’位置上不同官能基，對於此反應的影響。2,2'-di(phenylethynyl)-biphenyls undergo thermal cyclization reaction at high temperature (260℃) to yield compound 6. To probe the reaction mechanism, a series of 2,2'-di (phenylethynyl)-4,4'-disubstitued-biphenyl were synthesized and then were subjected to the reeaction conditions . In order to differentiate the diradical or benzocyclobutadiene mechanism, we added tetraphenylcyclo- pentadienone to trap the intermediate. Cyclooctatetraene derivatives, which were derived from addition reaction of tetraphenylcyclopentadienone and benzocyclobutadiene intermediate, were finally isolated. As a result, we concluded that the cyclization proceeds through the benzocyclobutadiene process. However the possibility of the diradical pathway couldn’t be completely excluded. We also explored the effects of the 4,4’-disubstitued functional groups on the thermal cyclization reaction.目錄 目錄……………………………………………………………..........……….....i 中文摘要………………………………………………………………............iii 英文摘要……..………………………………………………………..........….iv 圖目錄…………………………………………………………………..............v 表目錄………………………………………………………………….............vi 第一章 緒論……………………………………………………………............1 前言………………………………………….......................................1 1-1由乙炔基建構苯環的反應…………………………………......... 2 1-2 研究方向…………………………………………………….........7 1-3 研究目的…………………………………………………............11 第二章 結果與討論…………………………………………………..........…14 2-1 關於2,2’-二(苯乙炔基) -4,4’-雙取代聯苯的合成………............14 2-2 在高溫下以四苯基環戊二烯酮和2,2’-(苯乙炔基) -4,4’-雙取代-聯苯所進行的關環反應…..………………….......................……20 2-2.1 不含氮原子的化合物5c、5b、5f……………….....….…..21 2-2.2 化合物7c的結構鑑定…………………………….....…….22 2-2.3 化合物7f的結構鑑定…………………………….....……..28 2-2.4 含氮原子的化合物3、5a、5d、5e…………………….....…..29 2-3 反應機制的探討……………………...………………............…...32 2-3.1 不含氮系統的分子內關環反應………...……………....…32 2-3.2 不含氮系統的分子間關環反應…………………...............35 2-3.3實驗結果與反應機制的討論……………………….............36 第三章 結論…………………………………………………...………...........38 3-1 結論………………………………..……………...........…...……..38 3-2 未來方向…………………………..…………………..............…..38 第四章 實驗部分……………………………………………………..........…40 4-1實驗儀器與藥品………………………………………...….............40 4-2 合成步驟…………………………………………………..............42 參考資料………………………………………………………………............55 附錄I 化合物之1H與13C核磁共振光譜圖…………………………............58 附錄II 化合物X-ray晶體參數表及鍵長、鍵角資料………………..............8