镍催化环丁酮肟酯与芳基锌试剂的Negishi偶联反应

发展了一种镍催化环丁酮肟酯和芳基锌试剂之间Negishi偶联的方法.镍既作为亚胺自由基的引发剂,也作为芳基锌试剂与烷基自由基偶联反应的催化剂在反应中起作用.本方法可避免使用剧毒的氰化物,且具有很广的底物适应性和官能团兼容性,因此可能是一种具有潜在吸引力的高效合成烷基腈类化合物的新策略.初步的机理研究显示,该反应极可能经历自由基历程.     

Copper‐Catalyzed Amidation of Primary and Secondary Alkyl Boronic Esters

The oxidative copper‐catalyzed cross‐coupling of functionalized alkyl boronic esters with primary amides is reported. Through the identification of appropriate diketimine ligands, conditions for efficient coupling of both primary and secondary alkyl boronic esters with diverse primary amides, including acetamide, have been developed.     

Synthesis of enantiopure β-amino amides via a practical reductive amination of the corresponding β-keto amides

A convenient and efficient reductive amination for the preparation of chiral β-amino amides is developed utilizing microwave heating. A variety of chiral β-keto amides react with ammonium acetate and sodium cyanoborohydride to afford the desired functionalized amines in good yields. This improved procedure takes advantage of microwave heating to significantly accelerate the reaction and offers a convenient and effective method to access some interesting molecules containing primary amine functionalities.     

SYNTHESIS AND SPECTRAL STUDIES OF SOME NEW [(ALKOXYCARBONYLVINYL)ARYL- AND BENZYLSULFONYLMETHYL] SULFONES

Abstract

Some new 1,1,2-trisubstituted ethylenic sulfones have been prepared by the condensation of aryl- and benzylsulfonylmethylsulfonylacetic acid esters with araldehydes.     

AgOTf‐catalyzed transesterification of β‐keto esters

AgOTf proved to be an effective catalyst for the transesterification of β‐keto esters with primary, secondary and tertiary alcohols. The products were obtained in high yield within a reasonable reaction time period. The kinetics of the transesterification reaction were also studied and the reaction was found to follow second‐order kinetics. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on the Silylation Reaction of α,β-Epoxy Esters Synthesized by Darzen's Condensation Reaction

Me₃SiCl/Mg in HMPA was used for silylation of α,β-epoxy esters resulting in the corresponding β-silylated esters in a one pot reaction with reasonable yields.     

Study on properties of flame‐retardant cyanate esters modified with DOPO and triazine compounds

Ternary flame‐retardant modified cyanate ester blends (CEPG and CEPA) are formed by combining triazine compounds (TGIC or TAIC) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide with cyanate ester resin. The curing behaviors, thermal and mechanical properties, and the flame‐retardant properties are investigated. The results show that the CEPG and CEPA blends result in lower curing temperatures and glass transition temperatures than those of neat CE. Both of CEPG and CEPA blends significantly improve the flame‐retardant properties of CE resins, and UL‐94V‐0 rate is achieved for CEPG‐1.0 and CEPA‐0.5. The dielectric constant and loss of CEPA blends are lower than those of CEPG blend with the same phosphors content, and both of them are lower than those of neat CE. Therefore, the ternary flame‐retardant modified cyanate ester blends provide 2 ways for composites of producing printed circuit board with high flame‐retardant property and low dielectric constant and loss.     

A Straightforward Synthesis of Polyketides via Ester Dienolate Matteson Homologation

Application of ester dienolates as nucleophiles in Matteson homologations allows for the stereoselective synthesis of highly substituted α,β-unsaturated δ-hydroxy carboxyl acids, structural motifs widespread found in polyketide natural products. The protocol is rather flexible and permits the introduction of substituents and functionalities also at those positions which are not accessible by the commonly used aldol reaction. Therefore, this ester dienolate Matteson approach is an interesting alternative to the “classical” polyketide syntheses.     

Solvent-Free Acetylation of Thiols Under Catalysis of MgBr2·OEt2

Solvent-free protection of aromatic and aliphatic thiols with acetic anhydride was performed at room temperature under trace quantities of magnesium bromide ethyl etherate, affording rapid formation of various thiol esters in excellent yields.