IDENTIFICATION AND ABINITIO C-13 NMR ASSIGNMENT OF A PROANTHOCYANIDIN FROM PRUNUS-JACQUEMONTII

The concerted use of 1D and 2D multiple pulse NMR methods allowed the identification and assignment of a proanthocyanidin, ent-epiafzelechin(4alpha --> 8; 2alpha --> O --> 7)-epicatechin, extracted from the bark of Prunus jacquemontii. Reference deconvolution with the FIDDLE algorithm was successfully used for line shape correction of a C-13 spectrum with poor signal-to-noise ratio. Over 70 long-range proton-C-13 correlations were determined with the HMBC experiment, following modifications to improve instrument signal reproducibility, illustrating the value of this experiment when applied to systems with relatively few protons.