The Sensitized Photooxidation of Methoxycycloheptatrienes. The Synthesis of α-, β-, and γ-Tropolones

Article abstract of DOI:10.1246/bcsj.53.236

The sensitized photooxidation of 7-methoxycycloheptatriene (7-methoxytropilidene) afforded <4+2> cycloadduct (2), tropone, benzaldehyde and their 2-methoxy derivatives.Thermal isomerization of 2 followed by the treatment with alumina yielded 4-methoxytropone.The photooxidation of 1-methoxytropilidene gave 4-hydroxytropone and o-methoxybenzaldehyde, and the photooxidation of 3-methoxytropilidene followed by the treatment with triethylamine afforded 3-methoxytropone, tropone, and o-methoxybenzaldehyde.Characterization of the products and the mechanisms of the reactions are discussed.