7-methyl-tricyclo[5.3.0.0.1,6]Deca-2,4-dien-8-ones: The first examples of tricyclonorcaradienones in tautomeric equilibrium with the 7-methyl-bicyclo[5.3.0]1,3,5-decatrien-8-ones
7-methyl-tricyclo[5.3.0.0.1,6]Deca-2,4-dien-8-ones: The first examples of tricyclonorcaradienones in tautomeric equilibrium with the 7-methyl-bicyclo[5.3.0]1,3,5-decatrien-8-ones