Asymmetric synthesis of α‐substituted amino acids and amines by carbon–carbon bond formation in position α to the nitrogen

The asymmetric synthesis of α‐substituted α‐amino acids and propargylamines is described. As chiral auxiliary we used (S)‐(–)‐1‐dimethoxymethyl‐2‐methoxymethylpyrrolidine (SDMP, 1). Treatment of the amino acids or amines with SDMP 1 afforded the corresponding amidines C, which can be metalated and alkylated to yield the products D, which were hydrolyzed to give the desired α‐substituted α‐amino acids 20 and propargylamines 22. The method allows the enantioselective alkylation of amino acids and propargylamines in satisfactory chemical yields and fair to good enantioselectivity. The chiral auxiliary SDMP 1 is prepared from (S)‐proline in 4 steps.