50. “Bildung eines hochexplosiven Valenzisomeren des Indens aus Dilithiopentalen und Chlorcarben”
    Burger, U.; Bianco, B.
    Helv. Chim. Acta 1983, 66, 60-67.

The principal product of the reaction of dilithiopentalene (3) with methyllithium and methylene chloride is shown by difference-FT-NMR, spectroscopy to be tetracyclo[4.3.0.0^3,5.0^4,6]nona-1,7-diene (8). This laterally bridged benzvalene derivative explodes violently at temperatures as low as −40° when concentrated. Controlled rearrangement in diluted solution gives indene (4). The key step in the formation of the tetracyclic C₉H₈-compound 8 is suggested to be an intramolecular 1,4-carbene addition.

DOI : 10.1002/hlca.19830660107 

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