Corannulene. A Three-Step Synthesis1

Thermal cyclization of 7,10-diethynylfluoranthene (3) in the gas phase gives corannulene (2), the smallest bowl-shaped polycyclic hydrocarbon fragment of C60 with fullerene-like curvature. Bromocorannulene (10) and 1,6-dibromocorannulene (9) have also been obtained from flash pyrolysis of 7,10-bis(2,2-dibromovinyl)fluoranthene (8). Short, practical syntheses of several corannulene precursors from acenaphthenequinone are described which have made corannulene available in gram quantities.