Reagent-controlled enantioselectivity switch for the asymmetric fluorination of β-ketocarbonyls by chiral primary amine catalysis
作者:Yang'en You、Long Zhang、Sanzhong Luo
DOI:10.1039/c6sc03109a
日期:——
enantioselectivity switch was uncovered in the asymmetric α-fluorination of β-ketocarbonyls by a chiral primary amine catalyst. By a simple swap of fluorination reagents, both enantiomers of the quaternary fluorination adducts could be obtained with good yields and high enantioselectivity. Mechanistic studies disclosed dual H-bonding and electrostatic stereocontrolling modes for the catalysis.
Efficient Synthesis of Enantiomerically Pure β<sup>2</sup>-Amino Acids via Chiral Isoxazolidinones
作者:Hee-Seung Lee、Jin-Seong Park、Byeong Moon Kim、Samuel H. Gellman
DOI:10.1021/jo026738b
日期:2003.2.1
We report a practical and scalable synthetic route for the preparation of alpha-substituted beta-amino acids (beta(2)-amino acids). Michael addition of a chiral hydroxylamine, derived from alpha-methylbenzylamine, to an alpha-alkylacrylate followed by cyclization gives a diastereomeric mixture of alpha-substituted isoxazolidinones. These diastereomers are separable by column chromatography. Subsequent