92-83-1Relevant articles and documents
Carbenium Ions in Substitution Reactions at the Amino Nitrogen Atom
Yunnikova,Esenbaeva
, (2018)
Tropylium, xanthylium, and tritylium salts characterized by different stabilities differently reacted with biologically active amines. The reactions of tropylium perchlorate and tetrafluoroborate with 4-(cyclohepta-2,4,6-trien-1-yl)aniline was accompanied
High-Fidelity Dimerization of Xanthenyl Radicals and Dynamic Qualities of a Congested Ethane: Diethyl Dixanthenyl-9,9′-Dicarboxylate
Dubrawski, Zachary,Gelfand, Benjamin S.,Hogan, David T.,Sutherland, Todd C.
supporting information, (2021/12/23)
Exploration of the sterically-congested ethane diethyl dixanthenyl-9,9′-dicarboxylate has revealed the dynamic behavior arising from its congested C?C bond. Interlocking ‘geared’ substituents and favorable dispersion interactions around this bond result in a conformational preference for partially cofacial xanthene moieties both in solid state and as dilute solutions. The weak, centrally located C?C bond is 1.628 ? long and permits selective thermolysis to yield two carbon-centered ethyl xanthenyl-9-carboxylate radicals, which dimerize with high fidelity into the original sterically-congested ethane. Recombination of the radicals into this symmetrical head-to-head dimer is highly reproducible – by observing the equilibrium, the bond dissociation enthalpy was calculated to be 20.4 kcal ? mol?1. The substituents around the central carbon provide insufficient stabilization against oxygen, which consumes the radicals and unbalances the dimer-radical equilibrium.
Formation and Disproportionation of Xanthenols to Xanthenes and Xanthones and Their Use in Synthesis
Shi, Zeyu,Chen, Si,Xiao, Qiong,Yin, Dali
, p. 3334 - 3343 (2021/02/05)
A facile and versatile strategy employing TiCl4-mediated cyclization followed by a Cannizzaro reaction has been developed for the synthesis of various xanthene derivatives. The reaction proceeded smoothly to afford both xanthenes/xanthones or their sulfur derivatives and tolerated a wide range of electronically diverse substrates. Using this methodology, pranoprofen was synthesized in three steps in 59% overall yield from commercially available starting materials.