利用兩分子的1-碘-8-(苯乙炔基)萘環 (23a)於鈀金屬錯合物催化及碳酸銀活化下，加入参(呋喃-2-基)磷，進行耦合反應，合成7,14-二苯基-二苯駢[de,mn]稠四苯 (zethrene， 24a， R = Ph)，其結構為一非平面狀結構，由X-ray單晶分析獲得確認，扭曲角度約為43 o左右。並且根據X-ray單晶結構鍵長與單鍵雙鍵的差值分析可知，中心兩個六環是缺少芳香性的結構。
在調整產率中發現，無論是鈀金屬催化劑、銀化物的量、磷化物的反應性、溶劑等均扮演非常重要的角色。將1-碘-8-(苯乙炔基)萘環 (23a)、醋酸鈀、碳酸銀、参(呋喃-2-基)磷，溶於溶劑鄰二甲苯中，在溫度130 oC的溫度下，反應時間36個小時，可得到73%的產率。利用此合成方法，以製備13種多取代衍生物，產率為18 - 73%。比較產率可發現，當末端炔上芳香環取代基為拉電子性質或取代基立體效應較小時，反應性較佳；反之，當末端炔上芳香環取代基若為推電子特性或為較大取代基時，反應效果較差。

7,14-diphenyldibenzo[de,mn]naphthacene (zethrene, 24a) has been generated by the Pd-catalyzed cyclodimerization which used silver carbonate, Ag2CO3, and tris(furan-2-yl)phosphine, P(2-furyl)3 as cocatalyst. This structure which has been comfirmed by X-ray single-crystal diffraction analysis is non-planar and its twist angle about 43 o. The bond length and bond alternation in the crystal structures reveal that the central two six-membered rings lack aromaticity.
Systematic studies of the reaction conditions reveal that palladium catalyst, the amount of silver, reactivity of phosphine and solvent all play key roles. The reaction conditions have been optimized. Upon heating 1-iodo-8-(phenylethynyl)naphthalene (23a) in o-xylene at 130 oC about 36 hours with mixture of palladium(Ⅱacetate, Pd(OAc)2, silver carbonate and tris(furan-2-yl)phosphine can be obtained 73% yield. We have generated about 13 zethrene derivatives in this method and the yield from 18–73%. According to the yield, when the aryl-substitutent on terminal alkynes are donating characters or larger substituent, the yield is low; verse visa, when the aryl-substituent on terminal alkynes are withdrawing characters or small substitutent, the yield is better.

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