DETERMINATION OF ABSOLUTE-CONFIGURATIONS OF CARBINOLS OF ANNONACEOUS ACETOGENINS WITH 2-NAPHTHYLMETHOXYACETIC ACID-ESTERS

Structural elucidation of absolute configurations of the stereogenic c enters of acetogenins of Annonaceae was performed using the modified M osher's method. Thus, by replacing MTPA (methoxytrifluoromethylphenyla cetic acid) by 2-NMA (naphthylmethoxyacetic acid), we were able to det ermine the absolute configuration of the stereogenic centers of rollin iastatin-2 by simple analysis of the H-1 NMR spectra recorded at 400 M Hz. Indeed, by comparing the differences of chemical shifts between th e MTPA esters with those obtained with 8-NMA esters, we showed that we could take advantage of the long-range anisotropic effect of the naph thyl ring for the elucidation: of the unsymmetrical systems.