We have developed a chiral bisguanidinium salt catalyzed dynamic kinetic resolution of azlactones with oximes. A variety of chiral N-acyl amino acid oxime esters were generated with up to 97% ee and 99% yield. The products are useful in peptidesynthesis.
Group-Assisted Purification Chemistry for Asymmetric Mannich-type Reaction of Chiral <i>N</i>-Phosphonyl Imines with Azlactones Leading to Syntheses of α-Quaternary α,β-Diamino Acid Derivatives
作者:Haowei Zhang、Zhen Yang、Brian Nlong Zhao、Guigen Li
DOI:10.1021/acs.joc.7b02556
日期:2018.1.19
An asymmetric Mannich-type reaction between chiral N-phosphonyl imines and azlactones [oxazol-5(4H)-ones] has been established under convenient conditions at room temperature. The reaction was performed without using any bases, additives, or catalysts to achieve up to excellent chemical yields and diastereoselectivity for 32 examples. The α-quaternary syn-α,β-diamino acid products were purified simply
One-Pot Preparation of Oxazol-5(4<i>H</i>)-ones from Amino Acids in Aqueous Solvents
作者:Hikaru Fujita、Munetaka Kunishima
DOI:10.1248/cpb.c12-00291
日期:——
method for one-pot synthesis of oxazol-5(4H)-ones has been developed using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), which is available for the activation of carboxylic acids in an aqueous solvent. The oxazolones were prepared by the N-acylation of amino acids with carboxylic acids and the subsequent cyclodehydration of the resulting N-acylamino acids by the addition
[8+2] Formal Cycloaddition Reactions of Tropones with Azlactones under Brønsted Acid Catalysis and Synthesis of α-(2-Tropyl), α-Alkyl α-Amino Acids
作者:Francisco Esteban、Ricardo Alfaro、Francisco Yuste、Alejandro Parra、José Luis García Ruano、José Alemán
DOI:10.1002/ejoc.201301774
日期:2014.3
The reaction of tropones with azlactones catalyzed by Bronsted acids affords a variety of dihydro-2H-cyclohepta[b]furan derivatives, corresponding to a formal [8+2] cycloaddition process. They can easily be opened by nucleophiles to afford a new type of α,α-disubstituted α-amino acid (or peptide) containing seven-membered rings at the quaternary position.
Chemo-enzymatic asymmetric synthesis of amino acids. Enantioselective hydrolyses of 2-phenyl-oxazolin-5-ones.
作者:Rui-Lin Gu、Ik-Soo Lee、Charles J. Sih
DOI:10.1016/0040-4039(92)88111-h
日期:1992.4
Porcine pancreatic lipase and the lipase of Aspergillus niger catalyze the enantioselective hydrolysis of a series of 4-substituted-2-phenyl-oxazolin-5-ones to yield optically active ()-and ()-N-benzoyl aminoacids respectively.