Synthesis of Enantiomerically Enriched α-Bromonitriles from Amino Acids
Najeh Tka, Jamil Kraïem & Béchir Ben Hassine
pages 735-743, DOI:10.1080/00397911.2011.608142
http://www.tandfonline.com/doi/abs/10.1080/00397911.2011.608142
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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.
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