13 C NMR spectra of some o ‐carbonyl derivatives of naphthols

All the signals in the 13 C NMR spectra of o ‐carbonyl naphthol derivatives (i.e. o ‐hydroxy aldehydes, o ‐hydroxy methyl ketones and methyl esters of o ‐hydroxy acids) are assigned on the basis of the additivity rule of substituent‐induced shifts and selective 13 C{ 1 H} hetero‐decoupling experiments [sometimes in the presence of Yb(fod) 3 ]. The differences between the experimental chemical shifts and the values calculated on the basis of the additivity of substituent‐induced shifts are also given; these may be regarded as ‘intramolecular hydrogen bond‐induced shifts’.