
%0 Journal Article
%A Johns, RB 
%A Kriegler, AB 
%T Photolytic studies of cyclic unsaturated ketones. I. Irradiation products of 2-Methylcyclobutane-1,3-dione and its ethyl enol ether
%J Australian Journal of Chemistry
%D 1970/08/01
%V 23
%N 8
%P 1635-1640
%K 
%R https://doi.org/10.1071/CH9701635
%U https://www.publish.csiro.au/paper/CH9701635 
%X The photochemical rearrangement of 2-methylcyclobutane-1,3-dione and the ethyl ether of its enol (4) have been shown to follow the expected pathway for an &#945;, &#946;-unsaturated cyclobutenone. The enol ether, when irradiated in moist cyclohexane, forms 3-ethoxy-2-methyl-trans-crotonic acid (8) which is photo-isomerized to the cis-isomer (7). This latter isomer is the major product when the solvent is moist diethyl ether. It is suggested that the necessary rotation about a carbon-carbon single bond is solvent-dependent, and occurs in a &#946;,&#947;-unsaturated carboxylic acid formed as a reaction intermediate. 
