Highly Enantioselective α‐Cyanation with 4‐Acetylphenyl Cyanate

A highly effective asymmetric version of α‐cyanation of β‐keto esters and amides was developed with a Lewis‐acid catalyst. Thus, by using 10 mol % of a tridentate bisoxazoline–zinc(II) complex as the catalyst, a series of chiral nitriles containing a quaternary carbon center were obtained in excellent enantioselectivities (up to 97 % enantiomeric excess) and up to 95 % yield in the presence of 4 Å molar sieve at room temperature. For the first time, mild and active 4‐acetylphenyl cyanate was used instead of cyano‐hyperiodinate as the cationic cyano source for catalytic asymmetric α‐cyanation.