- Iron-Catalyzed Vinylzincation of Terminal Alkynes
-
Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C–H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.
- Huang, Qiang,Su, Yu-Xuan,Sun, Wei,Hu, Meng-Yang,Wang, Wei-Na,Zhu, Shou-Fei
-
p. 515 - 526
(2022/01/08)
-
- NOVEL COMPOUNDS AS INHIBITORS OF HISTONE DEACETYLASE 6 AND PHARMACEUTICAL COMPOSITION COMPRISING THE SAME
-
The present invention relates to a new compound having an inhibitory activity of histone deacetylase 6 (HDAC6), stereoisomers thereof, pharmaceutically acceptable salts thereof, a use thereof in the preparation of a drug, a pharmaceutical composition comprising them, a prophylactic or therapeutic method corresponding, and a method of preparing a new derivative 1,3,4-oxadiazole triazol, a novel compound having selective HDAC6 inhibitory activity being represented by the following chemical formula I.
- -
-
-
- Design, synthesis, and biological evaluation of novel 2′-methyl-2′-fluoro-6-methyl-7-alkynyl-7-deazapurine nucleoside analogs as anti-Zika virus agents
-
Zika virus (ZIKV) is a mosquito-borne flavivirus and outbreaks of ZIKV have been reported in Africa, Americas and other parts of the world lately. The ZIKV epidemic has received extensive attention due to its ability to cause serious medical consequences and complications such as microcephaly and Guillain-Barre syndrome in recent years. Up to now, there are no specific treatments or vaccines available for ZIKV infection, which highlights the urgent need for developing new therapies. In this work, we designed and synthesized a series of novel 6-methyl-7-acetylenenyl-7-deazapurine nucleoside analogs as potential inhibitors of ZIKV replication. The biological activities against ZIKV replication were evaluated and the structure-activity relationship (SAR) was also studied. Among the compounds evaluated, nucleoside analog 38 (EC50 = 2.8 ± 0.8 μM, EC90 = 6.8 ± 2.3 μM) showed the most potent anti-ZIKV activity with low cytotoxicity (CC50 = 54.1 ± 6.9 μM) in an A549 based cellular model. The inhibitory activity of 38 was about 5 times more potent than the positive control NITD008. Notably, 38 showed similar inhibition potency against different ZIKV strains (ZG-01 and MR766) in a variety of host cell types including SNB19, A549, Huh7, Vero. In addition, 38 (Kd = 1.87 μM) has a stronger affinity to ZIKV RNA-dependent RNA polymerase (RdRp) protein than NITD008 (Kd = 3.43 μM) in the non-phosphorylation assay. These results indicated that compound 38 may serve as a promising candidate in future anti-ZIKV drug discovery.
- Yao, Guoqiang,Yu, Jianchen,Lin, Cai,Zhu, Yujia,Duan, Anna,Li, Mengfeng,Yuan, Jie,Zhang, Jiancun
-
-
- Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
-
The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
- Liu, En-Chih,Topczewski, Joseph J.
-
p. 5308 - 5313
(2021/05/04)
-