- Ring expansion of cyclic β-amino alcohols induced by diethylaminosulfur trifluoride: Synthesis of cyclic amines with a tertiary fluorine at C3
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As the replacement of a hydrogen atom by a fluorine atom in a compound can have an important impact on its biological properties, the development of methods allowing the introduction of a fluorine atom is of great importance. The scope and limitations of
- Anxionnat, Bruno,Robert, Benoit,George, Pascal,Ricci, Gino,Perrin, Marc-Antoine,Gomez Pardo, Domingo,Cossy, Janine
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p. 6087 - 6099
(2012/09/11)
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- Stereochemical diversity in asymmetric cyclization via memory of chirality
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An enantiodivergent asymmetric cyclization of N-Boc-N-ω-bromoalkyl-α-amino acid derivatives has been developed. With potassium amide bases in DMF, cyclization proceeds with retention of configuration, while inversion of configuration was observed with lit
- Kawabata, Takeo,Matsuda, Seiji,Kawakami, Shimpei,Monguchi, Daiki,Moriyama, Katsuhiko
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p. 15394 - 15395
(2007/10/03)
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- Asymmetric Cyclization via Memory of Chirality: A Concise Access to Cyclic Amino Acids with a Quaternary Stereocenter
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N-(ω-Bromoalkyl)-amino acid derivatives, readily prepared from natural α-amino acids, gave cyclic amino acids with a quaternary stereocenter by treatment with potassium hexamethyldisilazaide in DMF. The chirality of parent amino acids was almost completely preserved during an enolate-formation and cyclization process, giving aza-cyclic amino acids in up to 98% ee in retention of configuration. This method is applicable to the asymmetric synthesis of azetidine, pyrrolidine, piperidine, and azepane derivatives. The asymmetric cyclization seems to proceed via an axially chiral enolate intermediate and not through a concerted SEi process. Copyright
- Kawabata, Takeo,Kawakami, Shimpei,Majumdar, Swapan
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p. 13012 - 13013
(2007/10/03)
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