132435-54-2

Upstream product

• 148766-15-8 (R,E)-3-but-2-enoyl-4-phenyloxazolidin-2-one 
• 160080-54-6 methyl (3S,2'S,5'R)-3-<5'-isopropyl-3',6'-dimethoxy-2',5'-dihydropyrazin-2'-yl>butanoate 

Relevant academic research and scientific papers

(S)- or (R)-3-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones: ideal Michael acceptors to afford a virtually complete control of simple and face diastereoselectivity in addition reactions with glycine derivatives.

[formula: see text] Enantiomerically pure (S)- or (R)-3-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones were found to serve as ideal Michael acceptors in addition reactions with achiral Ni(II) complexes of glycine Schiff bases. Virtually complete control of simple and face diastereoselectivity, observed in these reactions, combined with quantitative chemical yields renders this methodology synthetically superior to the previous methods.

Virtually complete control of simple and face diastereoselectivity in the Michael addition reactions between achiral equivalents of a nucleophilic glycine and (S)- or (R)-3-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones: Practical method for preparation of β-substituted pyroglutamic acids and prolines

This study demonstrates a new strategy for controlling the stereochemical outcome of the Michael addition reactions between nucleophilic glycine equivalents and α,β-unsaturated carboxylic acid derivatives: The addition reactions between achiral Ni(II)-complex of the Schiff base of glycine with o-[N-α-pycolylamino]acetophenone and (S)- or (R)-3-(E-enoyl)-4- phenyl-1,3-oxazolidin-2-ones were shown to occur at room temperature in the presence of nonchelating organic bases and, most notably, with very high stereoselectivity at both newly formed stereogenic centers. Thus, the chiral 4-phenyl-1,3-oxazolidin-2-one moiety was found to control efficiently both face diastereoselectivities of the glycine derived enolate and the C,C double bond of the Michael acceptor. The new strategy developed in this work is methodologically superior to previous methods, most notably in terms of generality and synthetic efficiency. Excellent chemical yields and diastereoselectivities, combined with the simplicity of the experimental procedures, render the present method of immediate use for preparing various 3-substituted pyroglutamic acids and related amino acids (glutamic acids, glutamines, prolines, etc.) available via conventional transformations of the former.

Stereochemically defined C-substituted glutamic acids and their derivatives. 1. An efficient asymmetric synthesis of (2S,3S)-3-methyl- and - 3-trifluoromethylpyroglutamic acids

An efficient asymmetric synthesis of biologically important (2S,3S)-3- methyl- and (2S,3S)-3-trifluoromethylpyroglutamic acid has been developed. The method consists of diastereoselective Michael addition reaction between ethyl crotonate or ethyl 4,4,4-trifluorocrotonate and a Ni(II) complex of the chiral non-racemic Schiff base of glycine with (S)-o-[N-(N- benzylprolyl)amino]benzophenone (BPB) followed by decomposition of the addition products by aq. HCl and treatment of the resultant glutamic acid derivatives with NH4OH to afford the target pyroglutamic acids along with recovery of the chiral auxiliary BPB. The stereochemical outcome of the addition reactions was found to be subjected to kinetic control. A mechanistic rationale for the observed stereochemical preferences is discussed.

Synthesis of (2S,3R)- and (2S,3S)-3-Methylglutamic Acid

Arndt-Eistert homologation of suitably protected (2S,3S)-3-methylaspartic acid occurs with retention of configuration at C-3 to give, ultimately, (2S,3R)-3-methylglutamic acid. (2S,3R)-3-Methylglutamic acid was also prepared in good yield via the conjugate addition of the lithiated anion of the bis-lactim ether of cyclo-(R-Val-Gly) to methyl (E)-butenoate.The analogous reaction performed using isopentyl (Z)-butenoate ultimately gave (2S,3S)-3-methylglutamic acid.Both conjugate additions occured with high diastereoselectivity.