79757-20-3Relevant academic research and scientific papers
Palladium-catalyzed α-arylation of zinc enolates of esters: Reaction conditions and substrate scope
Hama, Takuo,Ge, Shaozhong,Hartwig, John F.
, p. 8250 - 8266 (2013/09/24)
The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with i
Palladium-catalyzed α-arylation of 2-chloroacetates and 2-chloroacetamides
Molander, Gary A.,Traister, Kaitlin M.,Barcellos, Thiago
, p. 4123 - 4131 (2013/06/05)
A method has been developed for the Pd-catalyzed synthesis of α-(hetero)aryl esters and amides through a Suzuki-Miyaura cross-coupling reaction. This method avoids the use of strong base, does not necessitate inert or low temperature formation of reagents, and does not require the use of a large excess of organometallic reagent. Utilization of organotrifluoroborate salts as nucleophilic partners allows a variety of functional groups and heterocyclic compounds to be tolerated.
Palladium-catalyzed α-arylation of esters and amides under more neutral conditions
Hama, Takuo,Liu, Xiaoxiang,Culkin, Darcy A.,Hartwig, John F.
, p. 11176 - 11177 (2007/10/03)
Two procedures for the ∞-arylation of carbonyl compounds under conditions that are more neutral than those of reactions of aryl halides with alkali metal enolates are reported. The first procedure rests upon the development of catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) and the highly reactive dimeric Pd(I) complex {P(t-Bu)3]PdBr}2. By this procedure, zinc enolates prepared from ∞-bromo esters and amides react with aryl halides to form ∞-aryl esters and amides in high yields under mild conditions with 1-2 mol % catalyst and with remarkable functional group tolerance. By the second procedure, silyl ketene and silyl ketimine acetals react with aryl bromides in the presence of substoichiometric zinc fluoride, 1 mol % Pd(dba)2, and 2 mol % P(t-Bu)3 in DMF solvent at 80 °C. Reactions of zinc tert-butyl acetate and propionate enolates and trimethylsilyl ketene acetals of tert-butyl propionate and methyl isobutyrate with aryl bromides bearing electron-donating and potentially reactive, base-sensitive electron-withdrawing groups and with pyridyl bromides are reported. In addition, the diastereoselective coupling of phenyl bromide with an imide enolate bearing the Evans auxiliary is reported, and this study shows that racemization of base-sensitive stereocenters does not occur during the coupling process under these more neutral conditions. Copyright
Synthetic Applications of N-N Linked Heterocycles. Part 14. The Preparation of α-(4-Pyridyl)esters and α-(4-Pyridyl)nitriles by Regiospecific Attack of Ester and Nitrile Anions on Pyridinium Salts
Sammes, Michael P.,Lee, Cheuk Man,Katritzky, Alan R.
, p. 2476 - 2482 (2007/10/02)
Reactions between N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium tetrafluoroborate (1) and lithio-derivatives of esters and nitriles give only low yields of 1,4-dihydro-adducts (3) and (7) due apparently to competing proton abstraction from the pyridone methyl groups.This limitation with salt (1) appears only with C-H acids of pKa > 20.Decomposition of the adducts under free-radical conditions yields α-(4-pyridyl)-esters (4) and -nitriles (8) essentially quantitatively.The same pyridyl-esters and -nitriles may be prepared conveniently in good overall yields by the reaction between the appropriate lithium salts and N-triphenylmethylpyridinium salts.The scope and limitations of the method are discucced. 2-Methyl-N-triphenylmethylpyridinium tetrafluoroborate is reported for the first time.
