156721-18-5Relevant articles and documents
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
Soloshonok, Vadim A.,Ueki, Hisanori,Tiwari, Rohit,Cai, Chaozhong,Hruby, Victor J.
, p. 4984 - 4990 (2007/10/03)
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.
Asymmetric synthesis of unusual amino acids: Synthesis of optically pure isomers of N-indole-(2-mesitylenesulfonyl)-β-methyltryptophan
Boteju,Wegner,Qian,Hruby
, p. 2391 - 2404 (2007/10/02)
We have developed methods for the synthesis of the four optically pure isomers of β-methyltryptopham with the 2-mesitylenesulfonyl indole protecting group for peptide synthesis. Starting from 3-indoleacrylic acid, the β-methyl function was generated by a
Asymmetric synthesis of unusual amino acids: Synthesis of the optically pure isomers of indole-protected β-methyltryptophan suitable for peptide synthesis
Boteju,Wegner,Hruby
, p. 7491 - 7494 (2007/10/02)
The four isomers of N-indole-(2-mesitylenesulfonyl)-β-methyltryptophan have been synthesized in high optical purity using in part, asymmetric conjugate 1,4-additions followed by chiral imide enolate azidation and reduction.
