Silver-Catalyzed [3 + 3] Dipolar Cycloaddition of Trifluorodiazoethane and Glycine Imines: Access to Highly Functionalized Trifluoromethyl-Substituted Triazines and Pyridines
摘要:
Herein we disclose a silver-catalyzed [3 + 3] 1,3-dipolar cycloaddition reaction of trifluorodiazoethane with glycine imines. This reaction exhibits manifold remarkable features, such as easily available substrates, high regio- and diastereoselectivities, mild reaction conditions, and good yields across a broad spectrum of substrates. Moreover, swift transformations of the obtained tetrahydrotriazines provide efficient access to a diverse set of highly functionalized trifluoromethyl-substituted triazines and pyridines. Particularly noteworthy is that such trifluoromethylated 1,2,4-triazines demonstrate competent reactivity toward trans-cyclooctene (TCO) derivatives with second-order rate constants (k(2)) up to 99.24 M-1 s(-1), which represents the highest value involving 1,2,4-triazines to date.
Well-Designed Phosphine–Urea Ligand for Highly Diastereo- and Enantioselective 1,3-Dipolar Cycloaddition of Methacrylonitrile: A Combined Experimental and Theoretical Study
A novel chiral phosphine-urea bifunctional ligand has been developed for Cu-catalyzed asymmetric 1,3-dipolar cycloaddition of iminoesters with methacrylonitrile, a long-standing challenging substrate in asymmetric catalysis. Distortion-interaction energy analysis based on density functional theory (DFT) calculations reveals that the distortion energy plays an important role in the observed enantioselectivity
Application of the Cu(<scp>i</scp>)/TEMPO/O<sub>2</sub> catalytic system for aerobic oxidative dehydrogenative aromatization of pyrrolidines
作者:Zheng Luo、Yan Liu、Chao Wang、Danjun Fang、Junyu Zhou、Huayou Hu
DOI:10.1039/c9gc01932d
日期:——
A Cu(I)/TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)-catalyzed aerobic oxidative dehydrogenative aromatization reaction of fully saturated pyrrolidines to synthesize multi-substituted pyrroles was developed for the first time. The use of a non-precious metal catalyst, green oxidant and environmentally friendly solvent made the reaction more sustainable.
Asymmetric Construction of 3-Azabicyclo[3.1.0]hexane Skeleton with Five Contiguous Stereogenic Centers by Cu-Catalyzed 1,3-Dipolar Cycloaddition of Trisubstituted Cyclopropenes
作者:Hua Deng、Wu-Lin Yang、Fei Tian、Wenjun Tang、Wei-Ping Deng
DOI:10.1021/acs.orglett.8b01686
日期:2018.7.6
A highly diastereo- and enantioselective desymmetrization of prochiral cyclopropenes via a Cu(CH3CN)4BF4/Ph-Phosferrox complex catalyzed 1,3-dipolar cycloaddition of azomethine ylides was described. A variety of complex 3-azabicyclo[3.1.0]hexane derivatives bearing five contiguous stereogeniccenters and two all-carbon quaternarystereogeniccenters were directly synthesized as a single isomer in excellent
Highly Selective Copper-Catalyzed Asymmetric [3+2] Cycloaddition of Azomethine Ylides with Acyclic 1,3-Dienes
作者:María González-Esguevillas、Ana Pascual-Escudero、Javier Adrio、Juan C. Carretero
DOI:10.1002/chem.201500182
日期:2015.3.16
catalytic asymmetric 1,3‐dipolar cycloaddition of azomethineylides with acyclic activated 1,3‐dienes (and 1,3‐enynes) are described. Under copper catalysis, a selectivecycloaddition at the terminal γ,δ‐CC bond is observed. In addition, depending on the ligand used, either the exo or the endo adduct can be obtained with high selectivity. Under appropriate reaction conditions, the acyclic 1,6‐addition
描述了具有无环活化的1,3-二烯(和1,3-烯炔)的甲亚胺烷基化物催化不对称的1,3-偶极环加成反应的第一个例子。在铜催化下,观察到在末端γ,δ-CC键上的选择性环加成。另外,取决于所用的配体,可以高选择性地获得外型或内型加合物。在适当的反应条件下,检测到无环1,6加成产物,表明是逐步的机理。生成的C4-链烯基取代的吡咯烷是进一步进入多环系统的合适底物,如六氢色紫[4,3- b ]吡咯的制备和生物碱gracilamine的四环核心所强调的那样。