Dynamic Kinetic Resolution of Azlactones by a Chiral N, N-Dimethyl-4-aminopyridine Derivative Containing a 1,1′-Binaphthyl Unit: Importance of Amide Groups
A dynamic kinetic resolution (DKR) of azlactones in the presence of benzoic acid and a binaphthyl-based N,N-4-dimethylaminopyridine (DMAP) derivative 1i having two amide groups at the 3,3′-positions of a binaphthyl unit is developed. The reaction proceeded smoothly with a wide range of azlactones to provide α-amino acid derivatives with good to high enantiomeric ratios (er's). A multigram-scale reaction (2.5 g) for the DKR of azlactone 2d was also demonstrated, and the resulting product was converted to unnatural α-amino acid 6d′.
Peptide-catalyzed conversion of racemic oxazol-5(4 H)-ones into enantiomerically enriched α-amino acid derivatives
We report the development and optimization of a tetrapeptide that catalyzes the methanolytic dynamic kinetic resolution of oxazol-5(4H)-ones (azlactones) with high levels of enantioinduction. Oxazolones possessing benzylic-type substituents were found to perform better than others, providing methyl ester products in 88:12 to 98:2 er. The mechanism of this peptide-catalyzed process was investigated through truncation studies and competition experiments. High-field NOESY analysis was performed to elucidate the solution-phase structure of the peptide, and we present a plausible model for catalysis.
Metrano, Anthony J.,Miller, Scott J.
p. 1542 - 1554
(2014/03/21)
α-Hydroxymethylaspartic acid: Synthesis and absolute configuration by X-ray analysis of its derivative (+)-4-benzoylamino-4-carboxy-γ-butyrolactone
(+)-4-Benzoylamino-4-carboxy-γ-butyrolactone was synthesized, and its structure solved by direct methods and refined to R = 0.033.The molecule adopts a skew conformation with a C7-N1-C8-C12 torsion angle of 59.6(2) deg.The lactone ring has an envelope con
Wieczorek, Wanda,Bukowska-Strzyzewska, Maria,Olma, Aleksandra,Kaminski, Zbigniew J.,Leplawy, Miroslaw T.
p. 107 - 112
(2007/10/02)
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