 a general , 
 asymmetric synthesis of amino acid derivatives is reported . 
 masked 
 acyl cyanide ( mac ) reagents are shown to be effective umpolung synthons 
 for enantioselective additions to n - boc - aldimines . 
 
 the reactions are catalyzed by a modified cinchona alkaloid , which 
 can function as a bifunctional , hydrogen bonding catalyst , and afford 
 adducts in excellent yields ( 9098% ) and high enantioselectivities 
 ( up to 97.5:2.5 er ) . unmasking the addition products 
 gives acyl cyanide 
 intermediates that are intercepted by a variety of nucleophiles to 
 afford -amino acid derivatives . 
 notably , the methodology provides 
 an alternative method for peptide bond formation . 
Supplementary Material