Neutral and Anionic Square Planar Palladium(0) Complexes Stabilized by a Silicon Z-Type Ligand

Anionic [Pd(0)−X]⁻ ate complex were proposed as key intermediates in Pd-catalyzed cross-coupling for decades, but their isolation remained elusive. Herein, a chelating Lewis acidic bis(amidophenolato)silane is introduced as a strong Z-type ligand which enables the characterization of the first anionic [Pd(0)−X]⁻ ate complex. Intriguingly, these compounds and the neutral L−Pd(0) analogs exhibit a square planar coordination that is highly unusual for a d¹⁰ metal. Theoretical methods scrutinize the interaction between the Lewis acidic Si(IV) center and the late transition metal, while reactivity studies shed light on the potential role of anionic additives in oxidative addition reactions.     

赖氨酸修饰氧化石墨烯固体配体在C—N偶联中的应用研究

通过L-赖氨酸修饰氧化石墨烯(GO)制备了一种石墨烯杂化材料(Lys-GO).该材料作为一种固体配体用于铜催化的C—N偶联反应.考察了碱和温度对反应的影响.在100℃氮气气氛中,NaOH存在下,该固体配体辅助碘化亚铜催化一系列芳基化合物和氮杂化合物偶联,达到中等及以上收率.另外,该催化体系解决了均相催化剂和产品的分离困难和难循环使用的问题,降低了催化剂成本,减少了环境污染.     

Synthesis and Chemical Constitution of Diphenoxyphosphoryl Derivatives and Phosphonium Salts as Coupling Reagents for Peptide Segment Condensation

The reactions of diphenoxyphosphoryl chloride ((PhO) 2 P(O)Cl) and different chlorophosphonium salts ([R 3 PCl]X, R = (CH 3 ) 2 N, pyrrolidine, X = PF 6 m , BF 4 m ), respectively, with 7-aza-1-hydroxybenzotriazole (HOAt), 1-hydroxybenzotriazole (HOBt), hydroximinomalonitrile (HOxDCO), and ethyl hydroximinocyanoacetate (HOxO) are described. The structures of the new compounds, which are useful coupling reagents for epimerization-free peptide segment condensation, are discussed on the basis of their 1 H, 13 C, 31 P NMR, and IR spectra. The reactions of (PhO) 2 P(O)Cl lead to mixtures of O - and N -phosphorylated isomers of varying ratios. Contrary, reactions of chlorophosphonium salts yield exclusively one isomer.