Isotopic enrichment or a multipulse NMR experiment (INADEQUATE) was utilized to measure the 13C- 13C coupling constants for a collection of carboxylate esters. Significantly different values were measured for the C 2C 3 bond of endo- and exo-2-norbornyl acetates. The 13C- 13C coupling constants for the CαCO bond of substituted methyl and ethyl acetates (YCCO 2R: Y = Br, Cl, SH, CN, etc.) were in the range of 56 to 65Hz; the magnitude of J CC is substantially higher when the hybridization of Cα is sp 2 (as with benzoates and acrylates). The carbonyl carbons also displayed long range 13C- 13C couplings of 2.5 to 7.2 Hz.