IN QUEST OF TRICYCLO[4.4.1.0(4,11)]UNDECA-1,3,5,7,9-PENTAENE HIGHLY STRAINED, CYCLIC 10-PI-ELECTRON, POLYUNSATURATED HYDROCARBON - SYNTHESIS OF A METHOXYL-SUBSTITUTED DIHYDRO DERIVATIVE

Ketone 9, which can be rapidly prepared from 2-cyclohexenone in three steps, has been examined for its suitability as a template for the generation of the title hydrocarbon 5. The stepwise regiocontrolled introduction of two bromine atoms has resulted in the acquisition of 17, 22, or 23 depending upon conditions. The tribromo enone 18 has also been generated; although the more pivotal intermediate 24 has not been seen. Dehydrobromination experiments performed on these halogenated products have given rise to dienone 15 and trienone 19, both of which have proven to be rather sensitive compounds, The O-methylation of 19 could be accomplished to give 26, the maximally unsaturated member of this series generated to date. This tetraene polymerizes rapidly in its pure oily state or in solution when exposed to air.