C α ‐hydroxymethyl methionine: synthesis, optical resolution and crystal structure of its (+)‐ N α ‐benzoyl derivative

( R , S )‐Methionine was transformed into C α ‐hydroxymethyl methionine by a route involving C α ‐hydroxymethylation of 2‐phenyl‐4‐methylthioethyl‐5‐oxo‐4,5‐dihydro‐1,3‐oxazole. The absolute configuration of (−)‐ C α ‐hydroxymethyl methionine was elucidated to be ( S ) by chemical correlation with ( S ) (−)‐ C α ‐ethyl serine. Absolute structure determination (by single crystal X‐ray diffraction) on N α ‐benzoyl‐ C α ‐hydroxymethyl methionine confirmed the ( R )‐configuration for the (+)‐enantiomer. In addition, the X‐ray diffraction analysis showed that the C α,α ‐disubstituted glycyl residue adopts the fully extended (C 5 ) conformation. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.