High Temperature Synthesis of Bowl-Shaped Subunits of Fullerenes. II¹. From 9,9′-Bi-9H-fluorenylidene to Diindeno[l,2,3,4-defg; 1′,2′,3′,4′-mnop]chrysene

Thermal dehydrocyclization as well as isomerization reactions of 9,9′-bi-9H-fluorenylidene (2) have been investigated at temperatures above 700°C in the gas phase resulting in benz[e]indeno(l,2,3-hi)acephenanthrylene(3) and dibenzo[g,p]chrysene(4), respectively. If 4 is catalytically converted, benz[g]indeno[l,2,3,4-mnop]chrysene (5) is formed in resonable yields by dehydrocyclization. Separate pyrolysis runs of 3 and 5 at temperatures above 900°C give finally diindeno[l,2,3,4-defg;1′,2′,3′,4′-mnop]chrysene (1), a bowl-shaped subunit of buckminsterfullerenes, besides other polycyclic aromatic hydrocarbons.