Palladium-Catalyzed α-Arylation of Esters and Amides under More Neutral Conditions
作者:Takuo Hama、Xiaoxiang Liu、Darcy A. Culkin、John F. Hartwig
DOI:10.1021/ja036792p
日期:2003.9.1
aryl halides with alkalimetal 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 α-bromo esters and amides react with aryl halides to form α-aryl esters and amides in high yields under
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
作者:Michael P. Sammes、Cheuk Man Lee、Alan R. Katritzky
DOI:10.1039/p19810002476
日期:——
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
之间的反应ñ - (2,6-二甲基-4-氧代吡啶-1-基)吡啶鎓四氟硼酸盐(1)和酯的锂代衍生物和腈得到的1,4-二氢加合物仅低收率(3)和(7 )显然是由于从吡啶酮甲基中竞争质子的提取。盐(1)的这种限制仅在p K a > 20的CHH酸出现。在自由基条件下加合物的分解产生α-(4-吡啶基)-酯(4)和-腈(8)数量上。通过合适的锂盐和N-三苯基甲基吡啶鎓盐之间的反应,可以方便地以良好的总收率制备相同的吡啶基酯和-腈。讨论了该方法的范围和局限性。2-甲基-N首次报道了四氟硼酸-三苯基甲基吡啶鎓。
Palladium-Catalyzed α-Arylation of 2-Chloroacetates and 2-Chloroacetamides
作者:Gary A. Molander、Kaitlin M. Traister、Thiago Barcellos
DOI:10.1021/jo400488q
日期:2013.4.19
A method has been developed for the Pd-catalyzed synthesis of alpha-(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.
Gas-phase replacement σ0 substituent constants of heteroaryl groups1
作者:Nouria A. Al-Awadi、Rasha F. Al-Bashir、Osman M.E. ElDusouqui
DOI:10.1016/s0040-4039(00)99558-3
日期:1989.1
Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope
作者:Takuo Hama、Shaozhong Ge、John F. Hartwig
DOI:10.1021/jo401476f
日期:2013.9.6
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 isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching
报道了通过芳基溴化物与酯的烯醇锌的钯催化偶联实现酯的分子间α-芳基化。已经开发出三种不同类型的烯醇锌的反应。使用分离的 Reformatsky 试剂、使用由 α-溴代酯和活化锌生成的 Reformatsky 试剂以及使用氯化锌猝灭酯的碱金属烯醇化物生成的锌烯醇化物,可以高产率进行酯的 α-芳基化。使用烯醇锌代替碱金属烯醇化物大大扩展了酯的芳基化范围。该反应在室温或 70 °C 下与含有氰基、硝基、酯、酮、氟、烯醇化氢、羟基或氨基官能团的溴代芳烃以及与溴代吡啶发生。酯的范围包括无环乙酸酯、丙酸酯和异丁酸酯、α-烷氧基酯和内酯。使用带有受阻五苯基二茂铁基二叔丁基膦(Q-phos)或高反应性二聚Pd(I)络合物[P( t -Bu) 3 ]PdBr} 2 的催化剂进行酯的烯醇锌的芳基化。