Stereochemical assignment of naturally occurring 2,3-epoxy-2-methylbutanoate esters

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. Copyright © 2002 John Wiley & Sons, Ltd.