75761-88-5Relevant academic research and scientific papers
Migratory Insertion of Carbenes into Au(III)-C Bonds
Zhukhovitskiy, Aleksandr V.,Kobylianskii, Ilia J.,Wu, Chung-Yeh,Toste, F. Dean
, p. 466 - 474 (2018)
Migratory insertion of carbon-based species into transition-metal-carbon bonds is a mechanistic manifold of vast significance: it underlies the Fischer-Tropsch process, Mizoroki-Heck reaction, Ziegler-Natta and analogous late-transition-metal-catalyzed olefin polymerizations, and a number of carbonylative methods for the synthesis of ketones and esters, among others. Although this type of reactivity is well-precedented for most transition metals, gold constitutes a notable exception, with virtually no well-characterized examples known to date. Yet, the complementary reactivity of gold to numerous other transition metals would offer new synthetic opportunities for migratory insertion of carbon-based species into gold-carbon bonds. Here we report the discovery of well-defined Au(III) complexes that participate in rapid migratory insertion of carbenes derived from silyl- or carbonyl-stabilized diazoalkanes into Au-C bonds at temperatures ≥ -40 °C. Through a combined theoretical and experimental approach, key kinetic, thermodynamic, and structural details of this reaction manifold were elucidated. This study paves the way for homogeneous gold-catalyzed processes incorporating carbene migratory insertion steps.
EFFECT OF AN AROMATIC ESTER CONJUGATE BASE ON E1cB ESTER HYDROLYSIS. ALKALINE HYDROLYSIS OF FLUORENE-9-CARBOXYLATE ESTERS
Alborz, Manoochehr,Douglas, Kenneth T.
, p. 331 - 340 (2007/10/02)
A series of alkyl and substituted-aryl esters of fluorene-9-carboxylic acid have been synthesised and their alkaline hydrolyses studied.The pH profiles for hydrolysis indicated substrate ionisation at higher pH values (confirmed by spectral studies) and kinetic pK values for a number of these esters were obtained at 25 deg C.At high pH (pKa) the rate of hydrolysis became independent of pH with the observed rate constant in this high pH plateau region being called k'.A plot of logarithm (to base 10) of k' versus pKa of the conjugate acid of the appropriate leaving group consisted of two limbs, A and B, flanking a minimum.The slopes of the plots described above for regions A and B were -1.01+/-0.05 and +0.11+/-0.01 respectively.Region A, of high negative slope, was shown to correspond to an E1cB reaction of the title esters on the basis of linear free energy relationship arguments, the solvent deuterium kinetic isotope effect, activation parameters, and comparison with the 9-methyl-blocked analogues, as well as by the observation of saturation kinetics in aniline buffers at low pH.Region B was shown to correspond to a rate-determining step of attack of hydroxide ion on the limiting amount of ester in its neutral form.The low eliminative reactivity of fluorene ester anions was discussed along with factors considered in the literature for explaining elimination rates of ester anions.
