291763-98-9Relevant academic research and scientific papers
Design and synthesis of a new generation of 'NH'-Ni(II) complexes of glycine Schiff bases and their unprecedented C-H vs. N-H chemoselectivity in alkyl halide alkylations and Michael addition reactions
Ellis, Trevor K.,Soloshonok, Vadim A.
, p. 533 - 538 (2007/10/03)
Within this manuscript the synthesis of a new generation of Ni(II) complexes that contain a secondary rather than a tertiary amino group, as well as the unusual chemoselectivity, was demonstrated in alkyl halide alkylations and Michael addition reactions. The complete C-H chemoselectivity observed in these reactions suggests that coordination of nitrogen to a metal has a significant synthetic potential as protecting a group without the need of introducing a transient N-C substituent. These new complexes have also proven highly synthetically useful nucleophilic glycine equivalents for the simple and highly diastereoselective synthesis of β-substituted pyroglutamic acids via their reactions with chiral Michael acceptors. Georg Thieme Verlag Stuttgart.
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.
