Abstract Donor-acceptor-substituted vinylcyclobutanes 1 rearrange to cyclohexenes 2 at temperatures between 20 and 195 C. In solvents of low polarity,[2+ 2] cycloreversion competes with ring enlargement. Under acidic conditions, addition of nucleophiles to vinylcyclobutanes 1 with ring opening is observed. Stereospecificity of rearrangement and [2+ 2] cycloreversion are functions of temperature, solvent polarity and acid catalysis. ...
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