TY - JOUR
T1 - Michael addition reactions between chiral equivalents of a nucleophilic glycine and (S)- or (R)-3-[(E)-enoyl]-4-phenyl-1,3-oxazolidin-2-ones as a general method for efficient preparation of β-substituted pyroglutamic acids. Case of topographically controlled stereoselectivity
AU - Soloshonok, Vadim A.
AU - Cai, Chaozhong
AU - Yamada, Takeshi
AU - Ueki, Hisanori
AU - Ohfune, Yasufumi
AU - Hruby, Victor J.
PY - 2005/11/2
Y1 - 2005/11/2
N2 - This paper describes a systematic study of addition reactions between the chiral Ni(II) complex of the Schiff base of glycine with (S)-o[N-(N- benzylprolyl)amino]benzophenone and (S)- or (R)-3-[(E)-enoyl]-4-phenyl-1,3- oxazolidin-2-ones as a general and synthetically efficient approach to β-substituted pyroglutamic acids and relevant compounds. These reactions were shown to occur at room temperature in the presence of nonchelating organic bases and, most notably, with very high (>98% diastereomeric excess (de)) Stereoselectivity at both newly formed stereogenic centers. The stereochemical outcome of the reactions was found to be overwhelmingly controlled by the stereochemical preferences of the Michael acceptors, and the chirality of the glycine complex influenced only the reaction rate. Thus, in the reactions of both the (S)-configured Ni(II) complex and the Michael acceptors, the reaction rates were exceptionally high, allowing preparation of the corresponding products with virtually quantitative (>98%) chemical and stereochemical yields. In contrast, reactions of the (S)-configured Ni(II) complex and (R)-configured Michael acceptors proceeded at noticeably lower rates, but the addition products were obtained in high diastereo- and enantiomeric purity. To rationalize the remarkably high and robust Stereoselectivity observed in these reactions, we consider an enzyme-substrate-like mode of interaction involing a topographical match or mismatch of two geometric figures. Excellent chemical and stereochemical yields, combined with the simplicity and operational convenience of the experimental procedures, render the present method of immediate use for preparing various β-substituted pyroglutamic acids and related compounds.
AB - This paper describes a systematic study of addition reactions between the chiral Ni(II) complex of the Schiff base of glycine with (S)-o[N-(N- benzylprolyl)amino]benzophenone and (S)- or (R)-3-[(E)-enoyl]-4-phenyl-1,3- oxazolidin-2-ones as a general and synthetically efficient approach to β-substituted pyroglutamic acids and relevant compounds. These reactions were shown to occur at room temperature in the presence of nonchelating organic bases and, most notably, with very high (>98% diastereomeric excess (de)) Stereoselectivity at both newly formed stereogenic centers. The stereochemical outcome of the reactions was found to be overwhelmingly controlled by the stereochemical preferences of the Michael acceptors, and the chirality of the glycine complex influenced only the reaction rate. Thus, in the reactions of both the (S)-configured Ni(II) complex and the Michael acceptors, the reaction rates were exceptionally high, allowing preparation of the corresponding products with virtually quantitative (>98%) chemical and stereochemical yields. In contrast, reactions of the (S)-configured Ni(II) complex and (R)-configured Michael acceptors proceeded at noticeably lower rates, but the addition products were obtained in high diastereo- and enantiomeric purity. To rationalize the remarkably high and robust Stereoselectivity observed in these reactions, we consider an enzyme-substrate-like mode of interaction involing a topographical match or mismatch of two geometric figures. Excellent chemical and stereochemical yields, combined with the simplicity and operational convenience of the experimental procedures, render the present method of immediate use for preparing various β-substituted pyroglutamic acids and related compounds.
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U2 - 10.1021/ja0535561
DO - 10.1021/ja0535561
M3 - Article
C2 - 16248672
AN - SCOPUS:27544463710
SN - 0002-7863
VL - 127
SP - 15296
EP - 15303
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 43
ER -