We successfully synthesized a novel P-chirogenic diaminophosphine oxide 4, which was applied to catalytic enantioselective construction of quaternary carbon centers using Pd-catalyzed asymmetric allylic substitution with various beta-keto esters (up to 99% yield, 94% ee). Preliminary mechanistic studies indicated that two molecules of 8 coordinate to the Pd metal in a monodentate fashion, resulting in the formation of Pd complex 9 (Pd:8 = 1:2), which functions as the active species.
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Transition metal-catalyzed asymmetric reactions using P-chirogenic diaminophosphine oxides: DIAPHOXs.
Chem Pharm Bull (Tokyo)
September 2008
Graduate School of Pharmaceutical Sciences, Chiba University, Japan.
This review describes the development of a new class of chiral phosphorus ligands: amino acid-derived P-chirogenic diaminophosphine oxides, DIAPHOXs, and their application to several transition metal-catalyzed asymmetric allylic substitution reactions. Pd-catalyzed asymmetric allylic alkylation with cyclic beta-keto esters as prochiral nucleophiles was initially examined using P-chirogenic diaminophosphine oxide 1a, resulting in highly enantioselective construction of quaternary stereocenters. Mechanistic investigations revealed that 1a is activated by N,O-bis(trimethylsilyl)acetamide-induced tautomerization to afford a trivalent diamidophosphite species 13, which functions as the actual ligand.
View Article and Find Full Text PDFPd-catalyzed asymmetric allylic substitution reactions using P-chirogenic diaminophosphine oxides: DIAPHOXs.
Chem Rec
September 2007
Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan.
This paper describes the development of a new class of chiral phosphorus ligand: aspartic acid-derived P-chirogenic diaminophosphine oxides, DIAPHOXs, and their application to several Pd-catalyzed asymmetric allylic substitution reactions. Pd-catalyzed asymmetric allylic alkylation was initially examined in detail using diaminophosphine oxides 1a, resulting in the highly enantioselective construction of quaternary stereocenters. Mechanistic investigations revealed that 1a is activated by N,O-bis(trimethylsilyl)acetamide-induced tautomerization to afford a trivalent diamidophosphite species 12, which functions as the actual ligand.
View Article and Find Full Text PDFPd-catalyzed asymmetric allylic amination using aspartic acid derived P-chirogenic diaminophosphine oxides: DIAPHOXs.
Org Lett
September 2005
Graduate School of Pharmaceutical Sciences, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
[reaction: see text] A Pd-catalyzed asymmetric allylic amination using aspartic acid derived P-chirogenic diaminophosphine oxides (DIAPHOXs) is described. Asymmetric allylic amination of both linear and cyclic substrates proceeded at room temperature to give the chiral allylic amines in 72-99% ee.
View Article and Find Full Text PDFDevelopment of a new class of chiral phosphorus ligands: P-chirogenic diaminophosphine oxides. A unique source of enantioselection in Pd-catalyzed asymmetric construction of quaternary carbons.
J Org Chem
September 2005
Graduate School of Pharmaceutical Sciences, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
[reaction: see text] We have recently developed a new class of chiral phosphorus ligands: P-chirogenic diaminophosphine oxides. These pentavalent phosphorus compounds have been successfully applied to Pd-catalyzed asymmetric construction of tertiary and quaternary carbons. The actual ligand structure was the trivalent phosphorus species 17, which was generated in situ by BSA-induced P(V) to P(III) transformation of 6, the preligand.
View Article and Find Full Text PDFP-Chirogenic diaminophosphine oxide: a new class of chiral phosphorus ligands for asymmetric catalysis.
J Am Chem Soc
March 2004
Graduate School of Pharmaceutical Sciences, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
We successfully synthesized a novel P-chirogenic diaminophosphine oxide 4, which was applied to catalytic enantioselective construction of quaternary carbon centers using Pd-catalyzed asymmetric allylic substitution with various beta-keto esters (up to 99% yield, 94% ee). Preliminary mechanistic studies indicated that two molecules of 8 coordinate to the Pd metal in a monodentate fashion, resulting in the formation of Pd complex 9 (Pd:8 = 1:2), which functions as the active species.
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