Dications of Benzylidenefluorene and Diphenylmethylidene Fluorene: The Relationship between Magnetic and Energetic Measures of Antiaromaticity
作者:Catherine Do、Julianne Hatfield、Shirali Patel、D. Vasudevan、Cornelia Tirla、Nancy S. Mills
DOI:10.1021/jo101871q
日期:2011.1.7
Oxidation of m- and p-substituted benzylidene fluorenes to antiaromatic dications was attempted by electrochemical and chemical means. Electrochemical oxidation to dications was successful for benzylidene fluorenes with p-methoxy, p-methyl, p-fluoro, and unsubstituted phenyl rings in the 3-position; attempts to oxidize the m-substituted derivatives via electrochemistry were unsuccessful. Chemical oxidation
通过电化学和化学方法试图将间和对位取代的亚苄基芴氧化成抗芳族化合物。对于在3位上有对甲氧基,对甲基,对氟和未取代的苯环的亚苄基芴,电化学氧化成指示剂是成功的。尝试以氧化米取代经由电化学衍生物是不成功的。用SbF 5 / SO 2 ClF化学氧化得到9-[((4-甲氧基苯基)亚甲基] -9 H-干净的芴;所有其他取代的亚苄基芴的氧化产生产物混合物。GIAO方法计算出的化学位移与p-甲氧基取代的亚苄基芴指示表明,该计算令人满意地反映了该指示剂的磁性,并可能反映了所研究的其他指示剂的磁性。来自电化学氧化的氧化还原电势(一种指示剂的稳定性的度量)与另一种稳定性度量(每个指示剂与其中性前体之间的能量差计算值)显示出良好的线性关系。亚苄基芴的指示剂不如二苯基亚甲基芴的指示剂稳定。在每种类型的化合物中,带有p取代苯环的化合物比带有m的化合物更稳定。取代的苯环和带有被给电子基团取代的苯环的指示剂比带有被吸
An N-heterocyclic carbene-catalyzed switchable reaction of 9-(trimethylsilyl)fluorene and aldehydes: chemoselective synthesis of dibenzofulvenes and fluorenyl alcohols
作者:Yu-Chuan Ma、Jin-Yun Luo、Shi-Chu Zhang、Shu-Hui Lu、Guang-Fen Du、Lin He
DOI:10.1039/d1ob00065a
日期:——
carbene-catalyzed synthesis of dibenzofulvenes and fluorenyl alcohols was developed. In the presence of 10 mol% NHC (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and 4 Å molecular sieves, 9-(trimethylsilyl)fluorene undergoes an olefination reaction with aldehydes to produce dibenzofulvenes in 43–99% yields. However, on reducing the NHC loading to 1 mol% and with the addition of water, 9-(trimethylsilyl)fluorene
Effect of Reaction Conditions on the Kinetic and Activation Parameters for the Mild Introduction of Fluorine into Phenyl-Substituted Alkenes with Accufluor™ NFTh
作者:Stojan Stavber、Tjaša Sotler Pečan、Marko Zupan
DOI:10.1016/s0040-4020(00)00109-5
日期:2000.3
water had a negligible effect on the rate of the process, as well as the change of solvent polarity, indicating little change in the polarity of the rate-determining transition state in comparison with the reactants. Activation enthalpies (between 62 and 74 kJ mol−1) and activation enthropies (between −75 and −37 J mol−1 K−1) were determined for fluorination of 1 and 7 with NFTh in acetonitrile in the
protocol for the construction of 9-(diorganomethylidene)fluorenes through palladium-catalyzed coupling reactions of 2-iodobiphenyls with alkenyl bromides has been reported. The reaction proceeds through the C–H activation/oxidative addition/reduction elimination/intramolecular Heck coupling reaction to afford a series of 9-(diorganomethylidene)fluorenes with good yields. Control experiments demonstrate that