Highly Enantioselective Mannich Reactions with α-Aryl Silyl Ketene Acetals and Imines

Mannich reactions with chiral silicon Lewis acid activated acylhydrazones and α-aryl silyl ketene acetals and α-aryl,α-alkyl silyl ketene imines proceed efficiently and with good to excellent levels of both diastereoselectivity and enantioselectivity. The reactions provide access to α-aryl,β-hydrazido esters and α-aryl,α-alkyl,β-hydrazido nitriles, which are valuable analogs of β-amino acids.

以手性硅基路易斯酸（chiral silicon Lewis acid）活化的酰腙（activated acylhydrazones）、α-芳基硅基烯酮缩醛（α-aryl silyl ketene acetals）以及α-芳基、α-烷基硅基烯酮亚胺（α-aryl,α-alkyl silyl ketene imines）为底物的曼尼希反应（Mannich reactions）可高效进行，且同时具备良好至优异的非对映选择性与对映选择性。该类反应可得到α-芳基、β-肼基酯（α-aryl,β-hydrazido esters）以及α-芳基、α-烷基、β-肼基腈（α-aryl,α-alkyl,β-hydrazido nitriles），此类产物是β-氨基酸（β-amino acids）的重要类似物。