PERICYCLIC TRANSFORMATIONS OF TETRACYCLO2,903,8>TRIDECA-4,6,11-TRIENES, AND FORMATION OF DIHYDROSEMIBULLVALENES BY THERMAL INTRAMOLECULAR?4a+?2a>CYCLOADDITION IN SUBSTITUTED CYCLOOCTATRIENES

Article abstract of DOI:10.1016/0040-4020(80)88028-8

Cyclopentadienones react with certain cyclobutene dienophiles to give the anticipated carbonyl bridge adducts; these, on relatively mild thermolysis, yield dihydrosemibullvalene derivatives by a novel sequence including cheletropic loss of carbon monoxide, electrocyclic ring opening of immediate substituted bicyclo<4,2,0>octadienes, and intramolecular <_?4_a + _?2_a>cycloaddition of the derived cyclooctatrienes.Other pericyclic reactions of compounds related to those of the title compounds are also discussed.