2979-52-4Relevant articles and documents
Fe-catalyzed thioesterification of carboxylic esters
Magens, Silja,Plietker, Bernd
supporting information; experimental part, p. 8807 - 8809 (2011/09/16)
Second nature: Starting from shelf-stable aryl esters and thiols, a variety of carboxylic acid esters were transformed into the corresponding thioesters with no racemization of labile stereocenters (see scheme). The method was successfully applied in a native chemical-ligation-type peptide formation, which suggests that the thiol may act as a co-catalyst for future 1,2-additions of pronucleophiles to carboxylic esters.
Rate and Equilibrium Studies of the Reaction of Oxyanions with 2-Phenyloxazol-5(4H)-one
Chrystiuk, Edwin,Jusoh, Adelina,Santafianos, Dino,Williams, Andrew
, p. 163 - 168 (2007/10/02)
Equilibrium constants for the reaction of phenoxide ions with 2-phenyloxazol-5(4H)-one at 25 deg C and 1M ionic strength obey a Broensted relationship (log kOH/kArO = log K' = -173pKArOH - 15.81) and are not subject to steric effects from ortho-substituents.Both forward and reverse rate parameters exhibit steric effects, and the Broensted equations for meta- and para-substituted species are log kOH = -0.81 pKArOH + 9.75, and log kArO = 0.95pKArOH - 6.40.There is no break in the Broensted line in the region of pKArOH 5-11, consistent with a single transition-state.An upward deviation exists for oxyanions with low basicity (pKXOH 5); one of these oxyanions, betaine, has a solvent deuterium oxide isotope effect for its reaction with the oxazolone greater than 2, consistent with a general base mechanism for attack for these species.The results for nucleophilic attack of phenolate anions are in agreement with a concerted displacement at the carbonyl group.
