77647-98-4Relevant articles and documents
Structural and mechanistic studies of the base-induced Sommelet-Hauser rearrangement of: N -α-branched benzylic azetidine-2-carboxylic acid-derived ammonium salts
Tayama, Eiji,Watanabe, Kazutoshi,Sotome, Sho
supporting information, p. 6668 - 6678 (2017/08/16)
The base-induced Sommelet-Hauser rearrangement of N-α-branched benzylic azetidine-2-carboxylic acid ester-derived ammonium salts to obtain α-arylazetidine-2-carboxylic acid esters was investigated. The substrates, two diastereomeric salts (1S,2S,1′S)- and (1R,2R,1′S)-2, showed different reactivities. The rearrangement of (1S,2S,1′S)-2a proceeded with a perfect N-to-C chirality transfer to provide (R)-3a in 74% yield with 99% ee. However, the rearrangement of (1R,2R,1′S)-2a under the same conditions afforded (S)-3a in only 15% yield with a lower 66% ee, along with the competitive [1,2] Stevens rearrangement product 4a. Structural and mechanistic studies of this rearrangement were carried out to clarify the exact reason. Our results define the scope and limitations of the Sommelet-Hauser rearrangement and provide unique synthetic access to α-aryl amino acid derivatives.
Synthesis of spirocyclopropyl γ-lactams by tandem intramolecular azetidine ring-opening/closing cascade reaction: Synthetic and mechanistic aspects
Nocquet, Pierre-Antoine,Hazelard, Damien,Compain, Philippe
experimental part, p. 4117 - 4128 (2012/07/28)
The scope and limitations of a novel intramolecular azetidine ring-opening/closing cascade reaction affording spirocyclopropyl γ-lactams from azetidines in high regio- and stereoselectivity is reported. The key step of the process is a SN2-type ring-opening of TMSOTf-activated azetidine rings by silyl ketene acetals generated by treatment with TMSOTf and TEA. This study is a very rare example of nucleophilic ring-opening of azetidines that does not require formation of quaternary azetidinium salts by N-alkylation or the use of N-electron-withdrawing groups. Application of this process to 2-azetidinone system led to a complete change in reactivity and provide 6-aza-bicyclo[3.2.0]heptane derivatives via an unprecedented Mukaiyama aldol-like reaction involving an ester acceptor and a silyl imidate.
Preparation of β-lactams from azetidine-2-carboxylic acids and esters
Wasserman,Lipshutz,Tremper,Wu
, p. 2991 - 2999 (2007/10/02)
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