2-Carbethoxycyclanones of ring size 5–12 and 15 and their C-methyl derivatives have been prepared and studied in the UV and IR spectral regions. The enolizable β-ketoesters show a high intensity K band in the 255–263 mμ region associated with the chelated enolic species and two pairs of bands in the 6 μ double bond stretching region which correspond to the structural features of the keto and enol tautomers. The non-enolizable β-ketoesters show ...