10.1021/jacs.5b02561.s005 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 AlCl<sub>3</sub>‑Catalyzed Ring Expansion Cascades of Bicyclic Cyclobutenamides Involving Highly Strained <i>Cis</i>,<i>Trans</i>-Cycloheptadienone Intermediates American Chemical Society 2015 AlCl cyclobutenamide ci evidence tetracyclic molecules bicyclic cascade reactions electrocyclic ring opening DFT calculations Bicyclic Cyclobutenamides ketone 2015-04-29 00:00:00 Dataset https://acs.figshare.com/articles/dataset/AlCl_sub_3_sub_Catalyzed_Ring_Expansion_Cascades_of_Bicyclic_Cyclobutenamides_Involving_Highly_Strained_i_Cis_i_i_Trans_i_Cycloheptadienone_Intermediates/2172181 We report the first experimental evidence for the generation of highly strained <i>cis</i>,<i>trans</i>-cycloheptadienones by electrocyclic ring opening of 4,5-fused cyclobutenamides. In the presence of AlCl<sub>3</sub>, the cyclobutenamides rearrange to [2.2.1]-bicyclic ketones; DFT calculations provide evidence for a mechanism involving torquoselective 4π-electrocyclic ring opening to a <i>cis</i>,<i>trans</i>-cycloheptadienone followed by a Nazarov-like recyclization and a 1,2-alkyl shift. Similarly, 4,6-fused cyclobutenamides undergo AlCl<sub>3</sub>-catalyzed rearrangements to [3.2.1]-bicyclic ketones through <i>cis</i>,<i>trans</i>-cyclooctadienone intermediates. The products can be further elaborated via facile cascade reactions to give complex tri- and tetracyclic molecules.