Dimethylmalonyltrialkylphosphoranes: probing the steric effect on phosphorus and its stereochemical consequence in esterification reactions of chiral secondary alcohols
High chemical yields and high levels of stereochemical inversion are demonstrated in the phosphorane-mediated esterification reaction of chiral alcohols with non-hindered carboxylic acids through the incorporation of sterically non-hindered alkyl groups of phosphorus.
Dimethylmalonyltrialkylphosphoranes: New General Reagents for Esterification Reactions Allowing Controlled Inversion or Retention of Configuration on Chiral Alcohols
作者:James McNulty、Alfredo Capretta、Vladimir Laritchev、Jeff Dyck、Al J. Robertson
DOI:10.1021/jo026639y
日期:2003.2.1
through reaction of a trialkylphosphine with 2-chlorodimethylmalonate in the presence of triethylamine. These new reagents promote the condensation reaction of carboxylic acids with alcohols to provide esters along with trialkylphosphine oxide and dimethylmalonate. The condensation reaction of chiral secondary alcohols can be controlled to give either high levels of inversion or retention through a
Substituent Effect on the Enantiomer-Differentiating Reaction of Lithiomethyl<i>p</i>-Tolyl Sulfoxide with Meta- or Para-Substituted (<i>R</i>)-(−)-Menthyl Benzoates
para-substituents, with 2 equivalents of racemic lithiomethyl p-tolyl sulfoxide displays the feature of an enantiomer-differentiating reaction, affording the corresponding optically active β-keto sulfoxides. The degree and the direction of enantioselectivity were affected by the nature of the substituent on benzene ring. The electron-releasing substituents trend to increase the %e.e. value. The reversal in the configuration
Efficient Method for the Preparation of Carboxylic Acid Alkyl Esters or Alkyl Phenyl Ethers by a New-Type of Oxidation–Reduction Condensation Using 2,6-Dimethyl-1,4-benzoquinone and Alkoxydiphenylphosphines
A new-type of oxidation–reduction condensation proceeded smoothly to afford carboxylic acid alkyl esters or alkyl phenyl ethers in good to high yields by combined use of alkoxydiphenylphosphines (1...
synthesized and evaluated for their antibacterial activity against Gram-positive Staphylococcus aureus and Bacillus subtilis and Gram-negative Escherichia coli and in vitro antifungal activity against Candida albicans and Aspergillus niger. The results of antimicrobial activity demonstrated that the compounds 10, 20, and 21 were the most active ones among the synthesized compounds. The QSAR studies revealed