Fluorinated Bis(phenoxyketimine)titanium Complexes for the Living, Isoselective Polymerization of Propylene: Multiblock Isotactic Polypropylene Copolymers via Sequential Monomer Addition
摘要:
A series of bis(phenoxyketimine)titanium dichloride complexes were synthesized and evaluated as catalysts for living, isoselective propylene polymerization upon activation with methylaluminoxane (MAO). Catalysts bearing phenoxyketimine ligands with different substituents at the ortho and para. positions of the phenolate ring and substituents at the ketimine carbon were investigated. The identity of the ketimine substituent had the largest effect on the activity and isoselectivity of propylene polymerization. Complex 12/MAO promoted the living, isoselective polymerization of propylene ([m(4)] = 0.73, alpha = 0.94). This catalyst system was used for the synthesis of a number of block copolymers featuring isotactic polypropylene semicrystalline blocks and poly(ethylene-co-propylene) amorphous blocks. Several triblock samples with varying block lengths, a pentablock, and a heptablock copolymer were synthesized. Mechanical testing has revealed that each is elastomeric with elongations at break between similar to 790-1000%.
Ligand‐Promoted Rh
<sup>III</sup>
‐Catalyzed Thiolation of Benzamides with a Broad Disulfide Scope
作者:Yan‐Shang Kang、Ping Zhang、Min‐Yan Li、You‐Ke Chen、Hua‐Jin Xu、Jing Zhao、Wei‐Yin Sun、Jin‐Quan Yu、Yi Lu
DOI:10.1002/anie.201903511
日期:2019.7
A ligand‐promoted RhIII‐catalyzed C(sp2)−H activation/thiolation of benzamides has been developed. Using bidentate mono‐N‐protected amino acid ligands led to the first example of RhIII‐catalyzed aryl thiolation reactions directed by weakly coordinating directing amide groups. The reaction tolerates a broad range of amides and disulfide reagents.
Selective radical amination of aldehydic C(sp<sup>2</sup>)–H bonds with fluoroaryl azides via Co(<scp>ii</scp>)-based metalloradical catalysis: synthesis of N-fluoroaryl amides from aldehydes under neutral and nonoxidative conditions
作者:Li-Mei Jin、Hongjian Lu、Yuan Cui、Christopher L. Lizardi、Thiago N. Arzua、Lukasz Wojtas、Xin Cui、X. Peter Zhang
DOI:10.1039/c4sc00697f
日期:——
proven to be an effective metalloradical catalyst for intermolecularamination of C(sp2)–H bonds of aldehydes with fluoroaryl azides. The [Co(P1)]-catalyzed process can employ aldehydes as the limiting reagents and operate under neutral and nonoxidative conditions, generating nitrogen gas as the only byproduct. The metalloradical aldehydic C–H amination is suitable for different combinations of aldehydes
D 2h对称酰胺卟啉 3,5-Di t Bu-IbuPhyrin [Co( P1 )]的 Co( II ) 配合物已被证明是一种有效的金属基催化剂,用于 C(sp 2 )–H 键的分子间胺化醛与氟芳基叠氮化物。[Co( P1 )]-催化过程可以使用醛作为限制试剂并在中性和非氧化条件下运行,产生氮气作为唯一的副产品。金属基醛 C-H 胺化适用于醛和氟芳基叠氮化物的不同组合,产生相应的N-氟芳基酰胺的产率非常好。一系列机理研究支持 Co( II ) 催化的分子间 C-H 胺化的逐步自由基机制。
Selective annulation of benzamides with internal alkynes catalyzed by an electron-deficient rhodium catalyst
作者:Ping Zhang、Wenju Chang、Hongyun Jiao、Yanshang Kang、Wenxuan Zhao、Peipei Cui、Yong Liang、Wei-Yin Sun、Yi Lu
DOI:10.1016/j.cclet.2021.01.024
日期:2021.5
s with internalalkynes was successfully established under mild reaction conditions, with the assistance of Lewis acid silver salt. Particularly, electron-deficient benzamide substrates were smoothly transformed into the desired products in this catalytic system. The catalytic system showed a broad tolerance for different substituents on the aromatic rings or aryl, alkyl-substituted alkynes.
在路易斯酸银盐的辅助下,在温和的反应条件下成功建立了电子缺陷[Cp E RhCl 2 ] 2催化的N-五氟苯基苯甲酰胺与内部炔烃的环化反应。尤其是,在该催化体系中,缺电子的苯甲酰胺底物可以平稳地转化为所需的产物。催化体系显示出对芳环或芳基,烷基取代的炔烃上不同取代基的宽容度。
Rhodium(III)-Catalyzed C(sp<sup>2</sup>)–H Chemoselective Annulation to O-Cyclized Isochromen-imines from Benzamides
作者:Ping Zhang、Wenju Chang、Yan-Shang Kang、Wenxuan Zhao、Pei-Pei Cui、Yong Liang、Wei-Yin Sun、Yi Lu
DOI:10.1021/acs.orglett.0c03425
日期:2020.12.18
selective annulation of benzamides with internal alkynes has been achieved to the formation of O-cyclized isochromen-imines. Various substituents are well-tolerated under mild reaction conditions. Density functional theory calculations indicate that silver carbonate could act as a Lewis acid to assist the ligand to improve the chemical selectivity of the reaction in a catalyticsystem.
Rh(<scp>iii</scp>)-catalyzed C–H olefination of N-pentafluoroaryl benzamides using air as the sole oxidant
作者:Yi Lu、Huai-Wei Wang、Jillian E. Spangler、Kai Chen、Pei-Pei Cui、Yue Zhao、Wei-Yin Sun、Jin-Quan Yu
DOI:10.1039/c4sc03350g
日期:——
The oxidative olefination of a broad array of arenes and heteroarenes with a variety of activated and unactivated olefins has be achieved via a rhodium(III)-catalyzed C–H activation reaction. The use of an N-pentafluorophenyl benzamide directinggroup is crucial for achieving catalytic turnovers in the presence of air as the sole oxidant without using a co-oxidant.