10.1021/ja502252t.s004 Xiao-Na Wang Xiao-Na Wang Elizabeth H. Krenske Elizabeth H. Krenske Ryne C. Johnston Ryne C. Johnston K. N. Houk K. N. Houk Richard P. Hsung Richard P. Hsung Torquoselective Ring Opening of Fused Cyclobutenamides: Evidence for a <i>Cis,Trans</i>-Cyclooctadienone Intermediate American Chemical Society 2015 ci bicyclic cyclobutenamides 1 Fused Cyclobutenamides case conversion Torquoselective Ring ring opening vinyl cyclopentenones 2015-12-17 04:12:30 Dataset https://acs.figshare.com/articles/dataset/Torquoselective_Ring_Opening_of_Fused_Cyclobutenamides_Evidence_for_a_i_Cis_Trans_i_Cyclooctadienone_Intermediate/2039205 Electrocyclic ring opening of 4,6-fused cyclobutenamides <b>1</b> under thermal conditions leads to <i>cis,trans</i>-cyclooctadienones <b>2</b>-<i>E</i>,<i>E</i> as transient intermediates, en route to 5,5-bicyclic products <b>3</b>. Theoretical calculations predict that 4,5-fused cyclobutenamides should likewise undergo thermal ring opening, giving <i>cis,trans</i>-cycloheptadienones, but in this case conversion to 5,4-bicyclic products is thermodynamically disfavored, and these cyclobutenamides instead rearrange to vinyl cyclopentenones.