Stereochemical diversity in asymmetric cyclization via memory of chirality
Stereochemical diversity in asymmetric cyclization via memory of chirality
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DOI：
10.1021/ja0670761
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发表时间：
2006-12-06
影响因子：
15
通讯作者：
Moriyama, Katsuhiko
中科院分区：
文献类型：
--
作者：
Kawabata, Takeo;Matsuda, Seiji;Moriyama, Katsuhiko
An enantiodivergent asymmetric cyclization ofN-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 lithium amide bases in THF. Chirality of the parent amino acids was preserved during enolate formation and cyclization to give aza-cyclic amino acids in up to 98% ee with retention of configuration or inversion of configuration, depending on the reaction conditions. Thus, both enantiomers of cyclic amino acids with a tetrasubstituted stereocenter were prepared in high enantiomeric purity from readily availablel-α-amino acids. This protocol is also applicable to a spirocyclization and an intramolecular conjugate addition of α-amino acid derivatives, giving either of the enantiomers of a diazaspiro compound and a tetrahydroisoquinoline derivative, respectively, in up to 99% ee.
