Stereoselective Synthesis of Quaternary Center Bearing Azetines and Their β-Amino Acid Derivatives
作者:Christopher J. MacNevin、Rhonda L. Moore、Dennis C. Liotta
DOI:10.1021/jo7018202
日期:2008.2.1
We describe here the use of a stable, four-membered azetine heterocycle for the preparation of highly substituted β-amino acid derivatives. Imidazolidinone chiral auxiliaries were found to eliminate a competitive reaction pathway that had been present under previously reported conditions for azetine synthesis. The ephedrine derived imidazolidin-2-one 21 was allowed to react as its chlorotitanium enolate
l-Valinol and l-phenylalaninol-derived 2-imidazolidinones as chiral auxiliaries in asymmetric aldol reactions
作者:Taek Hyeon Kim、Gue-Jae Lee
DOI:10.1016/s0040-4039(99)02325-4
日期:2000.3
The chiral N-propionyl-2-imidazolidinones were synthesized in three steps from l-valinol and l-phenylalaninol and the aldol reaction of their boron enolate with aldehydes proceeded with high diastereoselectivity.
Investigation of the Mitsunobu Reaction of<i>N</i>-(2-Hydroxyethyl)-<i>N′</i>-Phenyl-Ureas
作者:Taek Hyeon Kim、Gue-Jae Lee、Mi-Hyun Cha
DOI:10.1080/00397919908086441
日期:1999.8
The Mitsunobu reaction of N-(2-hydroxyethyl)-ureas 1 using PPh3 and EtO2CN=NCO2Et led to the mixture of N- and O-alkylation products or a single isomer depending on the substrates.
Regiocontrolled Cyclization Reaction of <i>N</i>-(2-Hydroxyethyl)ureas by Transfer of Activation: One-Pot Synthesis of 2-Imidazolidinones
作者:Taek Hyeon Kim、Gue-Jae Lee
DOI:10.1021/jo9820061
日期:1999.4.1
Diastereoselective alkylation of chiral 2-imidazolidinone glycolates: asymmetric synthesis of α-hydroxy carboxylic acids
作者:Chong Chul Chun、Gue-Jae Lee、Jae Nyoung Kim、Taek Hyeon Kim
DOI:10.1016/j.tetasy.2005.07.036
日期:2005.9
Sodium enolates of chiral 2-imidazolidinone glycolates reacted with alkyl halides to produce alpha-alkylated products with high diastereoselectivities, which were readily removed by simple alkaline hydrolysis and were converted to the protected alpha-hydroxy carboxylic acids. The new stereogenic center was assigned the (R) -configuration by comparison with known compounds. (C) 2005 Published by Elsevier Ltd.