Sultine化合物的合成以及它作為雙自由基與鄰醌二烯前驅物的反應研究

Abstract

本論文主要探討以sultine當作non-Kekulé雙自由基及鄰醌二烯的前驅物，經熱化學反應脫除二氧化硫分子，可與親雙烯體進行Diels−Alder反應。我們成功的合成出2,5-雙取代□吩sultine (33e,f)，在鄰二氯苯的迴流溫度下生成non-Kekulé雙自由基中間體並與C60反應，而獲得1：1及2：1加成產物。經由變溫1H NMR實驗發現，C60單一加成產物其上六員環構形交換的活化能 (□Gc□) 分別是57e (14.6 kcal/mol) 及57f (14.0 kcal/mol)，與文獻記載的碳環衍生物之活化能值相近。以PM3理論計算，說明影響活化能 (□Gc□)的主要原因是六員環的鍵角與鍵長。嘗試以微波加速sultine 33a−f與C60反應，由迴流加熱2−24小時縮短至4分鐘，且單一及二次加成產物的比例由2−3：1提升至3.5−6：1。化合物57a經照光產生單態氧與2,5-二甲基□吩部份反應，生成新化合物62 (sulfine-enone) 及63 (endione)。 成功合成C-1含長碳鏈的烯類取代的benzosultine 98b−g，經加熱生成鄰醌二烯中間體，可進行[1,5]-氫轉移反應、分子內Diels−Alder加成反應與sulfolene異構化反應的競爭反應。碳鏈為丙烯及丁烯的化合物98b,c反應結果僅得到異構化產物105b,c；碳鏈為戊烯及己烯的化合物98d,e反應結果以異構化產物為主，三環結構其次，及極少量的[1,5]-氫轉移產物；碳鏈為庚烯及辛烯的化合物98f,g反應結果以異構化產物為主，其次是[1,5]-氫轉移產物，並沒有得到分子內Diels−Alder加成產物。我們也以相似的方法合成pyridinosultine 155和164a,b，其中含戊烯及己烯基取代的化合物164a,b經高溫封管進行分子內Diels−Alder加成反應，生成三環結構的化合物166a,b及異構化產物167a,b，總產率分別為73%及50%。

The goals of our research are to synthesize various sultines as precursors of non-Kekulé biradicals and o-quinodimethanes. When heated in the presence of dienophiles, the sultines underwent elimination of SO2, and underwent Diels−Alder reactions with the thus formed reactive intermediates. For example, 2,5-disubstituted thienosultines 33e,f gave rise to non-Kekulé biradicals under reflux condition in o-dichlorobenzene and gave 1:1 and 2:1 trapped products with [60]fullerene. Variable temperature 1H NMR experiments show that the activation energy (□Gc□) for the boat-to-boat inversion of C60 mono-adducts 57e and 57f are 14.6 and 14.0 kcal/mol, respectively. These □Gc□ are similar to those reported in the literatures for other carbocyclic derivatives. By PM3 theorical calculation, the main factors that affect □Gc□ are found to be bond angles and bond lengths of the six-membered ring that connects to [60]fullerene. Furthermore, the cycloaddition of sultines 33a−f and C60 was highly accelerated by microwave irradiation and the ratio of monoadduct vs. bisadduct also increased from 2−3:1 to 3.5−6:1. Two new compounds 62 (a sulfine-enone) and 63 (an endione) were isolated from decomposed 57a and were found to derive from self-sensitized singlet oxygen reaction on the 2,5-dimethylthieno moiety of 57a. Benzenosultines 98b−g containing long-chain olefines on C-1 were successfully synthesized in five steps. o-QDMs were generated by elimination of SO2 from these sultines which then underwent competitive pathways of reactions involving [1,5]-hydride shift, intramolecular Diels−Alder cycloaddition, and sultine to sulfolene isomerization. Compounds 98b,c containing allyl and 1-butenyl substituents led to sulfolene only. Heating compounds 98d,e gave mainly sulfolene as the major products, triycyclic compounds as minor products, and [1,5]-hydride shift products in the least amounts. Heating compounds 98f,g again gave sulfolenes as major products and minor [1,5]-hydride shift products, however, no Diels−Alder adducts were detected. Pyridinosultines 155 and 164a,b can be obtained from a similar method. When compound 164a,b containing 1-heptenyl and 1-hexenyl substituents were reacted in a sealed tube at high temperature, the triycycle 166a,b from the expected intramolecular Diels−Alder reaction and isomerized sulfolene 167a,b were obtained in 73% and 50% yields, respectively.