(E)-1,3-Dibenzoyl-2-trifluoromethylpropene and 3-Benzoyl-6-phenyl-2,4-bis(trifluoromethyl)-2H-pyran-2-ol: Novel Products from the Oxidation of 1-Phenyl-4,4,4-trifluorobut-2-yn-1-ol with Active Manganese(IV) Oxide

Article abstract of DOI:10.1107/S0108270193009047

Comparison of the two benzoyl groups attached to the ends of the propene chain reveals a slight shrinkage in the linking C-C bond when the group is conjugated to the propene double bond <1.490 (7= cf. 1.527 (6) Angstroem for the unconjugated group>.However, this is not reflected in the double bond itself, which at 1.312 (7) Angstroem is extremely short.In the substituted pyran, the benzoyl group has been forced out of conjugation by steric congestion but in this case too, even though the adjacent double bond is able to conjugate within the pyran ring, it still retains full double-bond character <1.328 (8) Angstroem>.Intermolecular hydrogen bonds between the benzoyl O atom and the alcohol group link the pyran molecules into infinite chains along a.