Kinetic control in the palladium-catalyzed synthesis of C2-symmetric hexabenzotriphenylene.: A conformational study

[GRAPHICS] The hitherto unisolated, thermodynamically unstable C-2-symmetric conformer of hexabenzotriphenylene (1) has been efficiently synthesized by palladium catalyzed cyclotrimerization of 9,10-didehydrophenanthrene (4). The barriers to conformational interconversion of 1 are examined experimentally and by computational studies.