Carbamoyl Anion Addition to <i>N</i>‑Sulfinyl Imines: Highly Diastereoselective Synthesis of α‑Amino Amides

Carbamoyl anions, generated from N,N-disubstituted formamides and lithium diisopropylamide, add with high diastereoselectivity to chiral N-sulfinyl aldimines and ketimines to provide α-amino amides. The methodology enables the direct introduction of a carbonyl group without the requirement of unmasking steps as with other nucleophiles. The products may be converted to α-amino esters or 1,2-diamines. Iterative application of the reaction enabled the stereoselective synthesis of a dipeptide. Spectroscopic and computational studies support an anion structure with η2 coordination of lithium by the carbonyl group.由N,N-二取代甲酰胺（N,N-disubstituted formamides）与二异丙基氨基锂（lithium diisopropylamide）生成的氨基甲酰阴离子（carbamoyl anions），以优异的非对映选择性与手性N-亚磺酰亚胺及酮亚胺（chiral N-sulfinyl aldimines and ketimines）发生加成反应，得到α-氨基酰胺（α-amino amides）。该合成方法可实现羰基（carbonyl group）的直接引入，无需像其他亲核试剂那般进行脱保护操作。所得产物可进一步转化为α-氨基酸酯（α-amino esters）或1,2-二胺（1,2-diamines）。通过迭代应用该反应，能够立体选择性合成二肽（dipeptide）。光谱学与计算化学研究证实，该阴离子的结构中存在羰基对锂的η²配位（η² coordination）。