Enantioselective Synthesis of α-Amino Acids from N-Tosyloxy β-Lactams Derived from β-Keto Esters
摘要:
A novel synthetic sequence has been developed to convert simple beta-keto esters into enantiomerically enriched alpha-amino acids. The key features of this sequence include the addition of azide to the C3 position of beta-keto ester derived N-tosyloxy-beta-lactams through a concomitant nucleophilic addition/ N-O bond reduction reaction, a mild CsF-induced N1 benzylation of a-azido monocyclic beta-lactams, the preparation of alpha-keto-beta-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-beta-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-beta-lactams is reported.
Enantioselective Synthesis of α-Amino Acids from N-Tosyloxy β-Lactams Derived from β-Keto Esters
摘要:
A novel synthetic sequence has been developed to convert simple beta-keto esters into enantiomerically enriched alpha-amino acids. The key features of this sequence include the addition of azide to the C3 position of beta-keto ester derived N-tosyloxy-beta-lactams through a concomitant nucleophilic addition/ N-O bond reduction reaction, a mild CsF-induced N1 benzylation of a-azido monocyclic beta-lactams, the preparation of alpha-keto-beta-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-beta-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-beta-lactams is reported.
Enantioselective Synthesis of α-Amino Acids from <i>N</i>-Tosyloxy β-Lactams Derived from β-Keto Esters
作者:Timothy B. Durham、Marvin J. Miller
DOI:10.1021/jo0162437
日期:2003.1.1
A novel synthetic sequence has been developed to convert simple beta-keto esters into enantiomerically enriched alpha-amino acids. The key features of this sequence include the addition of azide to the C3 position of beta-keto ester derived N-tosyloxy-beta-lactams through a concomitant nucleophilic addition/ N-O bond reduction reaction, a mild CsF-induced N1 benzylation of a-azido monocyclic beta-lactams, the preparation of alpha-keto-beta-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-beta-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-beta-lactams is reported.