Enantioselective Total Synthesis of the Neurotoxin Caramboxin

Herein, we report the first and efficient asymmetric total synthesis of the neurotoxin (−)-caramboxin. The key to success is the creation of a stereogenic center by using enantioselective catalytic phase-transfer α-alkylation of glycine imines, affording this unusual α-amino acid in good yields and up to 99% ee. This work validates the S configuration of the natural product.