Cycloocta-2,4,6-trien-l-one

Keywords cycloocta-2,4,6-trien-l-one, cycloocta-2,4-dien-l-one, inclusion complex, [2+2] photocycloaddition, cyclobutane... 

A cyclooctatriene was formed upon pyrolysis at high temperature (up to 350°C) of the exo-ortho adduct from benzene and 1,4-dioxene [12] the position of the double bonds, however, was not as expected for a ring-opened ortho adduct. The ortho adduct from benzene and 1,1-dimethoxyethene [12] is an acetal and with a trace amount of acid in methanol solution it is converted into cycloocta-2,4,6-trien-l-one (Scheme 50). 

Ring closure to cyclobutanes via valence isomerization of cycloocta-l,3,5-trienes is also possible when carbonyl functions are present in the ethane fragment. Thus, reaction of cyclohepta-2,4,6-trienone (tropone) with diazopropane gives 8,8-dimethylcycloocta-2,4,6-trienone (16, R = H), which rearranges quantitatively to 8,8-dimethylbicyclo[4.2.0]octa-2,4-dien-7-one (17, R = H).67... 

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