Synthesis of α-Fluorocarboxylates from the Corresponding Acids Using Acetyl Hypofluorite
作者:Shlomo Rozen、Aviv Hagooly、Rinat Harduf
DOI:10.1021/jo010677k
日期:2001.11.1
alpha-Fluorocarboxylic esters and acids were synthesized in good yields. The corresponding esters and acids were converted to their ketene acetals, and these enol derivatives reacted with AcOF made directly from fluorine. This route circumvents the problems associated with nucleophilic fluorinations such as various eliminations and rearrangements. alpha- and beta-branched carboxylic acid derivatives that cannot
of silyl enol ethers with simple chiral Brønsted acids, mainly due to bond flexibility between the proton and its chiral counterion, the orientational flexibility of the proton, and the fact that the proton sources available are limited to acidic compounds such as chiral carboxylic acids. To overcome these difficulties, we have developed a Lewis acid-assisted chiral Brønsted acid (LBA) system. The coordination
Enantioselective Protonation of Silyl Enol Ethers and Ketene Disilyl Acetals with Lewis Acid-Assisted Chiral Brønsted Acids: Reaction Scope and Mechanistic Insights
Enantioselectiveprotonation is a potent and efficient way to construct chiral carbons. Here we report details of the reaction usingLewisacid-assisted chiral Bronsted acids (chiral LBAs). The 1:1 coordinate complex of tin tetrachloride and optically active binaphthol ((R)- or (S)-BINOL) can directly protonate various silylenolethers and ketene disilyl acetals to give the corresponding α-aryl ketones
Deracemizing α‐Branched Carboxylic Acids by Catalytic Asymmetric Protonation of Bis‐Silyl Ketene Acetals with Water or Methanol
作者:Francesca Mandrelli、Aurélie Blond、Thomas James、Hyejin Kim、Benjamin List
DOI:10.1002/anie.201905623
日期:2019.8.12
protonation of bis‐silylketeneacetals. Our method delivers α‐branched carboxylic acids, including nonsteroidal anti‐inflammatory arylpropionic acids such as Ibuprofen, in high enantiomeric purity and high yields. The process can be incorporated in an overall deracemization of α‐branched carboxylic acids, involving a double deprotonation and silylation followed by the catalytic asymmetric protonation.