Preparative flash vacuum thermolysis. A short synthesis of cyclopenta[c,d]pyrene

Flash vacuum thermolysis (FVT) of 1-chloro-1-(pyren-1-yl)ethene at 1000 °C gives the combustion emittant cyclopenta[c,d]pyrene in good yields; the identification of 1-(pyren-1-yl)ethyne as an intermediate in the range 600–900 °C indicates that cyclopenta[c,d]pyrene is formed via an ethynyl–ethylidene carbene rearrangement.