Practical Stereo- and Regioselective, Copper(I)-Promoted Strecker Synthesis of Sugar-Modified α,β-Unsaturated Imines.

The regio- and stereoselective, Lewis acid catalyzed Strecker reaction between Me3SiCN and different aldimines incorporating a 2,3,4,6-tetrakis-O-pivaloyl-D-glucopyranosyl (Piv4Glc) chiral auxiliary has been worked out. Depending on the conditions used, high yields (up to 95%) and good diastereoselectivities (de > 86%) were achieved under mild conditions (Table 1), especially with CuBr ⋅ Me2S as catalyst. Our protocol allows the ready preparation of asymmetric β,γ-unsaturated α-amino acids such as (R)-2-amino-4-phenylbut-3-enoic acid (13; Scheme 2) and congeners thereof.