Synthesis of a Calicene Precursor for Retro-Diels-Alder Reactions

Article abstract of DOI:10.1002/hlca.19940770516

In view of retro-DIels-Alder reactions (RDA reactions), the calicene precursor 9 has been synthesized in a comparably simple four-step synthesis of dibromocarbene addition at dibenzobarrelene (10->11, 44percent), halogen-lithium exchange followed by reaction with cyclopentenone (11->12, 91percent) and H2O as well as HBr elimination (12->14->9, 43percent) (Scheme 5).First experiments with respect to the thermal behavior of 9 show that, although RDA reaction seems to be relatively easily occurring according to the results of 'Curie-Point" pyrolysis, only anthracene and no calicene 2 has been detected so far.