Synthesis of Enantiomerically Enriched α-Bromonitriles from Amino Acids

Abstract Two methods were investigated for the preparation of six chiral α-bromonitriles with different optic purities. The nitrous deamination of amino acids gives α-bromoacids, which react with chlorosulfonyl isocyanate followed by triethylamine to afford α-bromonitriles with moderate enantiomeric excess. However, the dehydration of corresponding α-bromoamids using thionyl chloride gives α-bromonitriles with good enantiomeric excess up to 94%. The use of phosphoryl chloride instead of thionyl chloride results in more than 30% racemization as determined by high-performance liquid chromatograpic analysis.