近年來，作為有機材料的多環芳香烴蓬勃發展，其中具有單重態雙自由基性質的多環芳香烴也是熱門的一項研究，本篇論文即是嘗試合成具雙自由基性質的多環芳香烴：二苯駢[a,de,j,mn]稠四苯衍生物以及環戊二烯[def]并茀衍生物，並在合成探討上分成三個主題。
主題一為嘗試合成4,13-雙(三甲苯基)四苯駢[a,de,j,mn]稠四苯(26)，利用自由基環化的方式合成26，在叔丁醇鉀(4當量)作為自由基起始劑下，嘗試許多不同反應條件，最終仍無法利用此方法環化得到26。
主題二為嘗試二苯駢[de,mn]稠四苯[2,1-b:8,7-b']二噻吩(44)，利用6, 12-二溴䓛(40)作為核心結構，與硼酸化合物39進行鈴木耦合反應後，加入1,3,5-三甲苯基格里納試劑進行親核加成反應，最後在路易士酸催化下環化得到44，因化合物的穩定性不佳，容易分解成其他結構，故在純化上無法順利分離。
主題三為嘗試合成環戊二烯[def]并茀(70)，在此部分期望在溫和的條件下合成環戊二烯[def]并茀的結構，利用聯苯二醛(66)進行親核加成反應，接著以酸催化環化的方式，得到副產物71、72、73。無法成功合成環戊二烯[def]并茀的結構的原因可能是應變能太大及芐基與碳-5的距離太遠而無法建立碳-碳鍵。

Polycyclic aromatic hydrocarbons (PAHs) with two electrons can be described as biradicaloid hydrocarbons that exhibit open shell character. In this study, the individual synthesis of biradicaloid PAHs tetrabenzo[a,de,j,mn]tetracene (26), dibenzo[4,5:10,11]tetraceno[2,1-b:8,7-b′]dithiophene (44), and cyclopenta[def]fluorene (70) was attempted.
The paper is segregated in three parts.

In part I, the attempted synthesis of 26, a promising reaction route utilizing t-BuOK via radical cyclization strategy applied to construct zethrene structures, was described. After trying many different conditions, the results revealed that intramolecular cyclization cannot be conducted via the radical pathway, and fragments of precursor 23 were obtained instead of the targeted product.

In part II, the attempted synthesis of 44 was presented. The structure of 44 was a zethrene derivative that contained thiophene units and could potentially display unique physical properties. To introduce the thiophene units, Suzuki coupling of 6,12-dibromochrysene(40) with thiophene boronic acid (39) was conducted. Mesityl groups were introduced by nucleophilic additions and then Lewis acid catalyzed cyclization was conducted. Finally, because of the easy decomposition of the zethrene derivative (44) under ambient conditions, we could not obtain the pure compound.

In part III, we sought to develop mild conditions for the utilization of acid-catalyzed cyclization for the synthesis of cyclopenta[def]fluroene derivative (70). When [1,1′-biphenyl]-2,2′-diylbis(mesitylmethanol) (68) was employed, the reaction afforded three by-products. Difficulties of cyclization of 70 can be attributed to the distance of benzyl alcohol and C-5 position on fluorene structure. Metal-catalyzed reaction with C–H bond activation via six member transition state could be a feasible synthetic method for solving this problem.

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