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.