Asymmetric Synthesis of α‐Amino Acids and N‐Protected α‐Amino Aldehydes by Addition of Chiral Vinyl Anions to Sulfonylimines

With enantiomeric excesses between 93 and 96%, the N-protected α-amino aldehydes 3, which are useful synthesis building blocks, are obtained by addition of the vinyl anion 2 to N alkylidene sulfonamides 1, after ozonolysis of the olefinic double bond. The aldehydes 3 can be converted under complete chelate control in Mukaiyama–aldol reactions to the esters 4. R for example C6H5, 4-CH3OC6H4; MEM = CH2OCH2CH2OCH3; Ar = 2,4,6-(CH3)3C6H2.