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Conjugate addition – enantioselective protonation reactions

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ABSTRACT

The addition of nucleophiles to electron-deficient alkenes represents one of the more general and commonly used strategies for the convergent assembly of more complex structures from simple precursors. In this review the addition of diverse protic and organometallic nucleophiles to electron-deficient alkenes followed by enantioselective protonation is summarized. Reactions are first categorized by the type of electron-deficient alkene and then are further classified according to whether catalysis is achieved with chiral Lewis acids, organocatalysts, or transition metals.

No MeSH data available.


Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.
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C40: Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.

Mentions: Enantioenriched α-amino phosphonic acids and their derivatives are important motifs that have been utilized by the pharmaceutical and agrochemical industries as α-amino acid analogues. Darses and co-workers reported a novel approach to the synthesis of enantioenriched α-amino phosphonates 170 via a rhodium(I) catalyzed enantioselective 1,4-addition of potassium aryltrifluoroborates 168 to dehydroaminophosphonates 169 (Scheme 40) [69]. α-Amino phosphonates 170 were obtained with high levels of enantioselectivity for electron-rich, neutral, and electron-poor aryltrifluoroborates 168. Electron-rich organoboron reagents (4-t-Bu, 4-MeO, and 3-MeO) gave slightly lower yields (51–77%) than the electron-poor reagents (65–86%), with potassium phenyltrifluoroborate giving the highest yield (91%). Phenylboronic acid was also shown to be a competent coupling partner, providing the corresponding product in 92% yield and 96.5:3.5 er.


Conjugate addition – enantioselective protonation reactions
Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4979737&req=5

C40: Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.
Mentions: Enantioenriched α-amino phosphonic acids and their derivatives are important motifs that have been utilized by the pharmaceutical and agrochemical industries as α-amino acid analogues. Darses and co-workers reported a novel approach to the synthesis of enantioenriched α-amino phosphonates 170 via a rhodium(I) catalyzed enantioselective 1,4-addition of potassium aryltrifluoroborates 168 to dehydroaminophosphonates 169 (Scheme 40) [69]. α-Amino phosphonates 170 were obtained with high levels of enantioselectivity for electron-rich, neutral, and electron-poor aryltrifluoroborates 168. Electron-rich organoboron reagents (4-t-Bu, 4-MeO, and 3-MeO) gave slightly lower yields (51–77%) than the electron-poor reagents (65–86%), with potassium phenyltrifluoroborate giving the highest yield (91%). Phenylboronic acid was also shown to be a competent coupling partner, providing the corresponding product in 92% yield and 96.5:3.5 er.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

The addition of nucleophiles to electron-deficient alkenes represents one of the more general and commonly used strategies for the convergent assembly of more complex structures from simple precursors. In this review the addition of diverse protic and organometallic nucleophiles to electron-deficient alkenes followed by enantioselective protonation is summarized. Reactions are first categorized by the type of electron-deficient alkene and then are further classified according to whether catalysis is achieved with chiral Lewis acids, organocatalysts, or transition metals.

No MeSH data available.