Determination of Absolute Configurations of Carbinols of Annonaceous Acetogenins with 2-Naphthylmethoxyacetic Acid Esters

Abstract

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 2-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.