18159-14-3Relevant academic research and scientific papers
A novel and convenient method for the preparation of 5-(diphenylmethylene)-1H-pyrrol-2(5H)-ones; synthesis and mechanistic study
Faigl, Ferenc,Deák, Szilvia,Mucsi, Zoltán,Hergert, Tamás,Balázs, László,Sándor, Boros,Balázs, Barbara,Holczbauer, Tamás,Nyerges, Miklós,Mátrav?lgyi, Béla
, p. 5444 - 5455 (2016/08/04)
An efficient, regioselective synthesis has been developed for the preparation of 5-(diphenylmethylene)-1H-pyrrol-2(5H)-ones from readily available 1H-pyrroles by sequential dibromination and selective organometallic bromine/lithium exchange followed by reaction with benzophenone. Comparison of various N-substituents was shown to demonstrate the high tolerance of the transformation to functional groups. The structures of the new products were determined by spectroscopic methods and confirmed by single-crystal X-ray diffraction measurement. In addition, theoretical study of the reaction mechanism and selective functionalization of the endocyclic double bond were also presented.
Revised Structures of N-Substituted Dibrominated Pyrrole Derivatives and Their Polymeric Products. Termaleimide Models with Low Optical Band Gaps
Choi, Dong-Sook,Huang, Shenlin,Huang, Mingsheng,Barnard, Thomas S.,Adams, Richard D.,Seminario, Jorge M.,Tour, James M.
, p. 2646 - 2655 (2007/10/03)
This paper describes an unexpected rearrangement/oxidation of N-substituted 2,5-dibromopyrroles upon treatment with HNO3. The bromides migrate from the 2,5-positions to the 3,4-positions with subsequent oxidation at the 2,5-positions to afford N-substituted 3,4-dibromomaleimides; the structure was confirmed by single-crystal X-ray analysis. The maleimides were then polymerized to the poly(N-substituted-3,4-maleimide)s with copper bronze. This constitutes a revision of structure for the monomers and polymers. The propensity for the dibromide migration was further confirmed by treatment of N-benzyl-2,5-dibromopyrrole under nonoxidative acidic conditions (p-TsOH) to afford N-benzyl-3,4-dibromopyrrole; both the starting material and product structures were confirmed by single-crystal X-ray analysis. Several termaleimides were prepared from pyrrole, maleic anhydride, and citraconic anhydride. These trimeric compounds underwent enormous shifts in their optical absorbance maxima (ca. 200 nm) when bases or nucleophilic solvents were added. Therefore, the termaleimides served as excellent models for the polymeric systems that had undergone shifts of 350-400 nm upon treatment with the same additives. Ab initio Hartree-Fock and density functional theory were utilized to assess the minimum conformation of the trimeric system. Both terminal maleimides appear canted 37° relative to the central maleimide unit. As the two end maleimide units were computationally forced into closer proximity, there was a dipolar stabilization that ensued between the two terminal maleimides with the formation of a 1,3-dioxetane. However, it is unlikely that there could be the formation of an isolable 1,3-dioxetane due to the large energy difference between the canted structure and the dioxetane. A significant decrease in the HOMO-LUMO energy of 13 kcal/mol was calculated upon formation of the 1,3-dioxetane, suggesting that nucleophiles likely move the canted structure more toward a planar form via addition to the α,β-unsaturated carbonyl units.
Bromination and Chlorination of Pyrrole and Some Reactive 1-Substituted Pyrroles
Gilow, H. M.,Burton, D. Edward
, p. 2221 - 2225 (2007/10/02)
Monobromination of pyrrole and 1-methyl-, 1-benzyl-, and 1-phenylpyrrole with 1 mol of N-bromosuccinimide in tetrahydrofuran results in the regiospecific formation of the 2-bromopyrroles.A little disubstitution is observed.Similarly, brominations with 2, 3, or 4 mol of NBS form primarily the di-, tri-, and tetrabromopyrroles, respectively.The thermodynamically more stable 3-bromopyrroles are the major monobrominated products observed when bromine is used as the brominating agent due to isomerization of the 2-bromopyrroles with hydrogen bromide.These reaction mixtures are further complicated because of disproportionation reactions.Chlorination with N-chlorosuccinimide gave results similar to those for the bromination with NBS, but the reaction is not as selective.
