Practical synthesis of an open geodesic polyarene with a fullerene-type 6:6-double bond at the center: diindeno[1,2,3,4-defg;1',2',3',4'-mnop]chrysene.

摘要: Diindeno[1,2,3,4-defg;1',2',3',4'-mnop]chrysene (1), the smallest possible alkene-centered C60 substructure with a curved pi-system, is obtained in 25-35% yield by flash vacuum pyrolysis of twisted 1,1'-dibromobifluorenylidene (2) on 100 mg scale at 1050 degrees C. At 1200 C, bowl-shaped hydrocarbon 1 rearranges to planar isomer diindeno[5,6,7,1-defg;5',6',7',1'-lmnop]chrysene (14) double 5/6 ring-expansion/ring-contraction. X-ray crystallography establishes that central carbon atoms are nearly 80% as pyramidalized (POAV angles = 9.0 and 11.6 for C60, respectively). A four-step synthesis has been developed prepare precursor mixture (E)- (Z)-isomers 39% overall from commercially available 9-fluorenone-1-carboxylic acid (10).