Efficient Cu‐catalyzed Asymmetric Alkylation and Application in the Total Synthesis of Phallotoxins and Virotoxins

Asymmetric alkylation is one of the most important methods for synthesis of chiral unnatural α‐substituted α‐amino acids. Herein, we reported the asymmetric alkylation catalyzed by Cu/(4S,2R)‐tBu‐Phosferrox catalyst. This catalyst exhibits the highest catalytic performance in the asymmetric alkylation at catalyst loading as low as 1.0 mol %, giving the desired products with up to 95% yield and >99% ee, which is the best results to date. Furthermore, this method was successfully applied to the scalable practical synthesize of unnatural amino acid 4,5‐OH‐Leu, which could be directly used in the total syntheses of phalloidin, phallacidin, other four phallotoxins and six virotoxins.