Stereochemical assignment of natural occurring 2,3-epoxy-2-methylbutanoate esters. J. Martín Torres-Valencia, Guadalupe I. León, J. Roberto Villagómez-Ibarra, Oscar R. Suárez-Castillo, Carlos Cerda-García-Rojas, Pedro Joseph-Nathan. DOI: 10.1002/pca.652
A method to determine the absolute configuration of 2,3-epoxy-2-methylbutanoate ester residues in natural products is presented, based on (i) the reduction of the ester function to yield a 2-methyl-1,2-butanediol, (ii) esterification of the obtained primary alcohol with either (R)-(+)- or (S)-(?)-Mosher's acid to afford the corresponding Mosher's ester, and (iii) 1H-NMR spectral comparison of the final product with that of the Mosher's esters prepared from 2-methyl-1,2-butanediols of known stereochemistry.