728-04-1Relevant articles and documents
Development of Axially Chiral Styrene-Type Carboxylic Acid Ligands via Palladium-Catalyzed Asymmetric C-H Alkynylation
Cui, Ru,Jin, Ruo-Xing,Li, Fei,Li, Yan,Wang, Xi-Sheng,Wu, Bing-Bing,Wu, Tian-Rui,Yang, Chi
, p. 8132 - 8137 (2021/11/01)
A weakly coordinated carboxylate-directed palladium-catalyzed atroposelective C-H alkynylation method for the development of novel axially chiral styrene-type carboxylic acids is disclosed. This transformation exhibits good yields (up to 85%), excellent enantiocontrol (up to 99% ee), and mild conditions. Notably, the synthetic utility of the resulting alkynyl carboxylic acid derivatives was demonstrated by various derivatizations as well as their potential as chiral ligands in asymmetric C-H activations.
Reactions of carbonyl compounds in basic solutions. Part 34. The mechanism of the base-catalysed ring fission of 2,3-diphenylcycloprop-2-en-1-one
Bowden, Keith,Burgess, Emma J.
, p. 1594 - 1600 (2007/10/03)
The rate coefficients for the base-catalysed ring fission of a series of 2-phenyl-3-(2-, 3-or 4-substituted phenyllcycloprop-2-en-1-ones to give the corresponding (E)-2,3-diphenylacrylic acids have heen determined in water at 30.0 °C, as well as for the unsubstituted compound at 40.0, 50.0 and 60.0 °C. The effects of meta-and para-substituents on the rates have been correlated using the Hammett equation to give a reaction constant, p, equal to ca 1.2 at 30 °C. For the unsubstituted compound, the activation parameters have been calculated and the kinetic solvent isotope effect has been studied. The effects of ortho-substituents on the rates appear to be mainly polar, rather than steric, in origin. The evidence indicates a mechanistic pathway which proceeds by addition of hydroxide anion to the ketone, which is rate-determining. The adduct suffers ring fission to give the final product via a carbanionic intermediate.
