1334591-49-9Relevant academic research and scientific papers
CHIRAL PHOSPHINES FOR PALLADIUM-CATALYZED ASYMMETRIC ALPHA-ARYLATION OF ESTER ENOLATES TO PRODUCE TERTIARY STEREOCENTERS IN HIGH ENANTIOSELECTIVITY
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Paragraph 00217-00218, (2013/03/26)
The disclosure provides new and improved methods for the Pd-catalyzed asymmetric α-arylation of ester compounds, which produce the corresponding α-aryl moiety in high enantioselectivity (generally >90% ee). The present methods utilize a palladium catalyst supported by new (R)-H8-BINOL-derived monophosphine ligands. The method is applicable to a wide variety of aryl triflate substrates having variations in both electronic and steric properties. These aryl triflate substrates react with various α-alkyl (Z)- and/or (E)-0-trimethylsilyl ketene acetals in the presence of a Pd catalyst, (R)-H8-BINOL-derived monophosphine ligand, and a mild activator, for example, LiOAC, to provide the asymmetric α-arylation of ester compounds in high ee.
An enantioselective, intermolecular α-arylation of ester enolates to form tertiary stereocenters
Huang, Zhiyan,Liu, Zheng,Zhou, Jianrong
supporting information; experimental part, p. 15882 - 15885 (2011/11/13)
In transition-metal catalyzed, asymmetric α-arylation of carbonyl compounds, formation of tertiary centers with high enantioselectivity is a longstanding problem, due to easy enolization of the monoarylation products. Herein, we report such examples using a palladium catalyst supported by a new, (R)-H8-BINOL-derived monophosphine. Silyl ketene acetals, together with a weakly basic activator, were used as equivalents of ester anions, and they reacted smoothly with aryl triflates in excellent enantiomeric excess (ee). The usefulness of the reaction was demonstrated in a gram-scale synthesis of (S)-Naproxen in 92% ee.
