Diastereoselective Cyanation of α‐Keto Amides Derived from N‐Phenyl Camphorpyrazolidinone and Camphorsultam

The diastereoselective cyanation of α‐keto amides using trimethylsilyl cyanide in the presence of a Lewis acid is described. The corresponding O‐acetylated cyanohydrins are obtained in good to high levels of stereoselectivities. The predominance of products with the S absolute configuration at the newly generated stereogenic center was deduced from single crystal X‐ray analysis. ¹³C NMR data suggest that a preferential s‐cis conformation was formed by the chelation of a Lewis acid to the dicarbonyl oxygen atoms.