Proaromaticity: Organic Charge-Transfer Chromophores with Small HOMO-LUMO Gaps
作者:Yi-Lin Wu、Filip Bureš、Peter D. Jarowski、W. Bernd Schweizer、Corinne Boudon、Jean-Paul Gisselbrecht、François Diederich
DOI:10.1002/chem.201001051
日期:2010.8.16
prepared and investigated to validate proaromaticity as a concept for reducing HOMO–LUMOgaps in push–pull chromophores. Analyses of IR, 1H NMR, and UV/Vis/NIR spectra in conjunction with molecular structures determined by X‐ray diffraction show that these push–pull quinoids have significant charge‐separated ground states. This feature results in small optical gaps (near IR region) and diatropic magnetic
制备并研究了基于醌或扩展醌的新颖的供体和/或受体取代的交叉共轭碳环,其环半径为radianannulene,并验证了前芳香性是减少推挽发色团中HOMO-LUMO间隙的概念。红外分析11 H NMR,UV / Vis / NIR光谱以及X射线衍射确定的分子结构表明,这些推挽式醌类化合物具有明显的电荷分离基态。如原子核无关的化学位移(NICS)计算所建议的那样,此功能会导致较小的光学间隙(靠近IR区域)和碳环化合物内部的变质磁性环境。NICS的结果以及对醌类间隔基的键长分析提供了有力的支持,即芳香性,即在基态下芳构化的两性离子介观贡献是有效的。推挽式四(乙炔二基)-扩展的醌型生色团代表了第一个芳香族的a基环戊二烯。
Switchable Chemoselectivity for Organocatalytic, Asymmetric Malononitrile Addition to <i>ortho</i>-Formyl Chalcones
Chemoselective 1,2- and 1,4-addition of malononitriles to ortho-formyl chalcones using cinchona alkaloid based bifunctional chiral organocatalysts has been shown by tuning the electronic nature of the malononitriles. Alkyl (hard) malononitriles undergo an asymmetric 1,2-addition followed by oxa-Michael reaction cascade to afford 1,3-disubstituted isobenzofurans with high enantio- and diastereoselectivity
A new route to phenylenedimalononitrile and the analogues using palladium-catalyzed carbon-carbon bond formation
作者:M. Uno、K. Seto、M. Masuda、W. Ueda、S. Takahashi
DOI:10.1016/s0040-4039(00)98550-2
日期:——
Phenylenedimalononitrile and the analogues, which are key intermediates in the synthesis of TCNQ and the analogues, are prepared directly by the Pd-catalyzed reaction of-diiodoarenes with malononitrile anion.
Decyanation–(hetero)arylation of malononitriles to access α-(hetero)arylnitriles
作者:L. Reginald Mills、Purvish Patel、Sophie A. L. Rousseaux
DOI:10.1039/d2ob00236a
日期:——
Quaternary α-(hetero)arylnitriles are desirable biologically relevant products, however the existing methods for their synthesis can be unselective or require the use of undesirable reagents, such as cyanide salts. Herein we report a one-pot method for transnitrilation-mediated decyanation–metalation of disubstituted malononitriles, followed by treatment with (hetero)aryl electrophiles to access quaternary
Herein, we report a light-driven, radical-type cyano migration in the absence of a photocatalyst, enabling a chemo-divergent synthesis of (Z)-alkenyl nitriles and ketones. Trifluoromethyl thianthrenium salt (TT–CF3+OTf–) plays multiple roles: (a) absorbing light to generate trifluoromethyl radicals to initiate the reaction and (b) forming α-thianthrenium cyano species by in situ capture of TT• +. (Z)-Alkenyl