Intramolecular dehydro Diels-Alder reactions of diarylacetylenes: Switching between benzo[b]- and benzo[c]fluorenones as products by controlling the rearrangement of cyclic allene intermediates

Article abstract of DOI:10.1021/jo0498213

Thermal cyclization of 1-[2-(arylethynyl)phenyl] -3-trimethylsilylpropynones affords a mixture of benzo[b]fluorenones and benzo[c]fluorenones. The ratio of the two isomers can be efficiently varied between 100:0 and 0:100 by introducing substituents with