Determination of absolute configurations of carbinols of annonaceous acetogenins with 2-naphthylmethoxyacetic acid esters

Structural elucidation of absolute configurations of the stereogenic centers of acetogenins of Annonaceae was performed using the modified Mosher's method. Thus, by replacing MTPA (methoxytrifluoromethylphenylacetic acid) by 2-NMA (naphthylmethoxyacetic acid), we were able to determine the absolute configuration of the stereogenic centers of rolliniastatin-2 by simple analysis of the (1)H NMR spectra recorded at 400 MHz. Indeed, by comparing the differences of chemical shifts between the MTPA esters with those obtained with 8-NMA esters, we showed that we could take advantage of the long-range anisotropic effect of the naphthyl ring for the elucidation: of the unsymmetrical systems.