Ethyl 2-trans-cinnamoyl­aceto­acetate

Low-temperature X-ray diffraction data show that ethyl 2-acetyl-3-oxo-5-phenyl­pent-4-enoate (C₁₅H₁₆O₄) exists in the same single enol tautomer in the crystal phase as indicated by spectroscopic data for the compound in solution. The adopted conformation is that with the longest possible conjugation combined with the enol H atom being bonded to the O atom closest to the most electronegative substituent in the planar cinnamoyl acetate unit. Weak hydrogen bonds of the type C—H⋯O are suggested.