6-Acetoxycyclohexa-2,4-dienones are found to undergo a rapid reaction in methanol/water under mildly basic conditions to give an acyclic ketoester as the major product for 6-phenyl and 6-methyl substrates. Reaction monitoring by UV spectroscopy indicates the formation of an unsaturated ketone reaction intermediate (lambda (max) 275 nm, R = Ph) and the transient appearance of a highly conjugated species. Reaction of the 6-phenyl substrate (4.95 x 10(-6) s(-1)) is 2-fold faster than the 6-methyl substrate (2.47 x 10(-6) s(-1)). The reaction rate is first order with respect to substrate concentration, and the final step in the reaction is ps-dependent. No cleavage was observed for a substrate lacking an acetyl substituent. A reaction mechanism for C-C cleavage is proposed involving a benzene oxide-oxepin interconversion. The possible relevance to the catalytic mechanism of the intradiol catechol dioxygenases is discussed
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.