Towards redox-switchable organocatalysts based on bidentate halogen bond donors
作者:E. Engelage、H. Hijazi、M. Gartmann、L.-M. Chamoreau、B. Schöllhorn、S. M. Huber、C. Fave
DOI:10.1039/d0cp06612e
日期:——
Redox-active bidentate halogen bond donors based on halopyridinium groups as halogen-bond donating units were synthesized and their structures were elucidated by X-ray diffraction analyses and DFT calculations. Via reversible twofold reduction, these dicationic species can be transformed to neutral compounds which should be much weaker Lewis acids. The corresponding electrochemical data were obtained
Cα-substituted 4-methylpyridines have been N-lithiated and reacted with chlorotrimethylsilane and other electrophiles. The lithiated Cα-NMe2 substituted intermediate shows an interesting dichotomy of behavior towards electrophiles: It represents the borderline between compounds for which an extreme N or Cα regio-nucleophilicity is observed.
Lithiation of 2-Me3SiCHRC5H4N(R = H or SiMe3): influence of solvent on the nature of the product (from X-ray structure determinations) and asymmetric induction. A note on the lithiation of some analogous 3- and 4-methylpyridines
作者:Rocco I. Papasergio、Brian W. Skelton、Paul Twiss、Allan H. White、Colin L. Raston
DOI:10.1039/dt9900001161
日期:——
Metallation of 2-Me3SiCHRC5H4N (R = H or SiMe3) using LiBun in hexane, and in the presence of diethyl ether, and the ditertiary amines tmen (N,N,N′,N′-tetramethylethylenediamine) or sp [(–)sparteine] yields crystalline lithium complexes. These have been characterized using X-ray diffraction data for [Li2-C(SiMe3)2C5H4N}2-CH(SiMe3)2C5H4N}](1), [Li[2-C(SiMe3)2C5H4N]}2](2), [Li(tmen)2-C(SiMe3)2C5H4N}](3)
使用LiBu n在己烷中,在乙醚和二叔胺tmen(N,N,N ',N'-四甲基乙二胺)的存在下使用LiBu n对2-Me 3 SiCHRC 5 H 4 N(R = H或SiMe 3)进行金属化)或sp [(–)sparteine]产生结晶的锂配合物。这些已使用,其特征在于X射线衍射数据[李2-C(森达3)2 C ^ 5 ħ 4 N} 2-CH(森达3)2 C ^ 5 ħ 4 N}](1),[Li [2-C(SiMe 3)2 C 5 H 4 N]} 2 ](2),[Li(tmen)2-C(SiMe 3)2 C 5 H 4 N}](3),[Li(OEt 2)[2-CH(SiMe 3)C 5 H 4 N]} 2 ](4),[Li(tmen)[2-CH(SiMe 3)C 5 H 4 N] } 2 ](5)和[Li(sp)2-CH(SiMe 3)C 5 H 4 N}](6)。在(1),(3),(4)和(6)烃基充当η
Comparison of Carbon−Silicon Hyperconjugation at the 2- and 4-Positions of the <i>N</i>-Methylpyridinium Cation
作者:Kathryn Hassall、Sofia Lobachevsky、Jonathan M. White
DOI:10.1021/jo048384p
日期:2005.3.1
pyridinium cations 6a−c and 4-trialkylsilylmethylpyridinium cations 5a−c were prepared and investigated using 29Si and 13C NMR and single-crystal X-ray crystallography. Systematic differences in the 29Si chemical shifts and 29Si−13C one-bond coupling constants for these cations suggested that the Si−CH2 bond interacts more strongly at the 2-position of the electron-deficientpyridinium ring than at
制备了N-甲基-2-三烷基甲硅烷基甲基吡啶阳离子6a - c和4-三烷基甲硅烷基甲基吡啶阳离子5a - c并使用29 Si和13 C NMR和单晶X射线晶体学进行了研究。这些阳离子在29 Si化学位移和29 Si - 13 C单键耦合常数上的系统差异表明,Si-CH 2键在缺电子吡啶鎓环的2位上比在4位上的相互作用更强。位置。吡啶鎓阳离子5b和6b的X射线结构证明了这一结果。
Approach to Trisubstituted 3-Aminopyrrole Derivatives by Yb(OTf)3-Catalyzed [4+1] Annulation of 2-Azadiene with Me3SiCN
we found a novel approach to the simple and practical synthesis of 3-aminopyrrolederivatives through the four-component coupling reaction of a functionalized silane, a nitrile, an aldehyde, and trimethylsilyl cyanide by Yb(OTf) 3 -catalyzed annulation of a 2-azabutadiene with trimethylsilyl cyanide. In this paper, we also disclose a single-step transformation of the 3-aminopyrrole framework into the