32222-42-7Relevant academic research and scientific papers
1-Methyl-1-azacyclohexa-2,3-diene(N-B)borane - Generation and interception of an unsymmetrical isodihydropyridine
Drinkuth, Stefan,Groetsch, Stefan,Peters, Eva-Maria,Peters, Karl,Christl, Manfred
, p. 2665 - 2670 (2001)
3-Bromo-1-methyl-1,2,5,6-tetrahydropyridine(N-B)borane (7) was prepared from 3-bromopyridine by conversion to 3-bromo-1-methylpyridinium iodide, hydrogenation of the latter with sodium tetrahydroborate and treatment of the resulting 3-bromo-1-methyl-1,2,5,6-tetrahydropyridine (6) with borane-dimethyl sulfide. Whereas no trapping product of the possible intermediate 1-methyl-1-azacyclohexa-2,3-diene (4) could be observed on treatment of 6 with potassium tert-butoxide in the presence of furan, the subjection of 7 to the same conditions produced the hexahydroepoxyquinoline derivatives 8a-c. Treatment of 7, dissolved in styrene, with sodium bis(trimethylsilyl)amide furnished the hexahydrocyclobutapyridine derivatives 9a-c. The six-membered cycloallene 1-methyl-1-azacyclohexa-2,3-diene(N-B)borane (10) must be regarded as the key intermediate en route to 8 and 9.
Cyanometallates as halogen bond acceptors
Ormond-Prout, Johnathan E.,Smart, Paul,Brammer, Lee
, p. 205 - 216 (2012)
Two families of halopyridnium hexacyanometallate salts, (3-XpyMe) 3[M(CN)6] and (3,5-X2pyMe)3[M(CN) 6] (X = I, Br; 3-XpyMe = N-methyl-3-halopyridinium; 3,5-XpyMe = N-methyl-3,5-dihalopyridinium; M = Cr, Fe, Co), have been synthesized and characterized by single crystal X-ray diffraction. Five of the six members of each family are characterized as isostructural compounds, two structures are reported as solvates, (3-IpyMe)3[Fe(CN)6]?2MeCN (2?2MeCN) and (3,5-Br2pyMe)3[Cr(CN) 6]?4H2O (10?4H2O), and the solvate (3-IpyMe)3[Co(CN)6]?2MeCN (3?2MeCN) has been characterized in addition to the unsolvated 3. All halogens participate in halogen bonding, forming C-X???NC(M) halogen bonds and in one case a C-Br???O halogen bond (in 10?4H2O). The halogen bond distances are shorter than the corresponding sum of van der Waals radii, and stronger interactions are formed by iodine than bromine (I???N 2.789(7)-3.116(7), RIN 0.790-0.883; Br???N 2.884(3)-3.166(2), RBrN 0.848-0.931). Longer halogen bonds are formed in 10?4H2O (Br???N 3.041(6)-3.380(6), RBrN 0.894-0.994) due to competition from O-H???N hydrogen bonding. All halogen bonds have interaction geometries at the halogen close to linearity (most have C-X???N > 165°; smallest angle is 154.1(3)°). The geometry of interaction of the halogen bond donor (C-X) with the cyanide ligand either suggests interaction predominantly with the exo lone pair of the nitrogen atom (C≡N? ??X > 145°) or predominant involvement of the C≡N π-bond in the halogen bond (C≡N???X Fe > Co, and this is discussed in the context of metal-to-cyanide π-back-donation.
Heteroaromatic cation-based chromophores: Synthesis and nonlinear optical properties of Alkynylazinium salts
Caneque, Tatiana,Cuadro, Ana M.,Alvarez-Builla, Julio,Perez-Moreno, Javier,Clays, Koen,Marcelo, Gema,Mendicuti, Francisco,Castano, Obis,Andres, Jose L.,Vaquero, Juan J.
supporting information; experimental part, p. 6323 - 6330 (2011/01/13)
A variety of alkynylazinium cationic (D-π-A+) chromophores were prepared in good yields by the reaction of bromoazinium (pyridinium, quinolinium, and isoquinolinium iodides) with alkynes under Sonogashira conditions. The analysis of the experimentally recorded spectra is supported by quantum chemical calculations using restricted configuration interaction and density functional methods. First-order hyperpolarizabilities of (D-π-A +) azinium-based cations as a new class of second-order nonlinear optical (NLO) chromophores were also studied by hyper-Rayleigh scattering experiments and computational procedures. Copyright
Excellent correlation between substituent constants and pyridinium N-methyl chemical shifts
Huang, Sha,Wong, Jesse C.S.,Leung, Adam K.C.,Chan, Yee Man,Wong, Lili,Fernendez, Myrien R.,Miller, Amanda K.,Wu, Weiming
experimental part, p. 5018 - 5020 (2009/12/01)
Substituents on the pyridinium ring of N-methylpyridinium derivatives, especially those on the 2- or 4-position, have a large effect on the 1H and 13C NMR chemical shifts of the N-methyl group. Reasonable correlations between the chemical shift changes and the resonance substituent constants are observed. The dual substituent parameter approach provides an excellent correlation when a combination of polar and resonance substituent constants is employed.
Electronic Effects on the Menschutkin Reaction. A Complete Kinetic and Thermodynamic Dissection of Alkyl Transfer to 3- and 4-Substituted Pyridines
Arnett, Edward M.,Reich, Ronald
, p. 5892 - 5902 (2007/10/02)
The relationship between kinetic and thermodynamic parameters is explored for quaternization of a series of pyridines (mostly 3- and 4-substituted) with several methylating and ethylating reagents in several solvents.The reaction with methyl iodide in acetonitrile is reversible at temperatures in the neighborhood of 100 deg C so that the effect of substituents on free energy, enthalpy, and entropy for activation of the forward and reverse reactions and for the overall quaternization can be determined.A variety of experimental techniques was used to obtain rates over a range of 1013 and to determine enthalpies and entropies of reaction.The results are self-consistent and agree generally with isolated published values for similar systems.The relationship between thermodynamic and activation parameters is examined, and a gross disparity is found between free energy and enthalpy behavior compared with that of the entropies.A consistent picture of the quaternization reaction emerges, based on many studies using a variety of mechanistic probes.The transition state is "early" as far as bond formation to the base in concerned but "late" in terms of bond rupture between the transferring alkyl group and the leaving group with solvent reorganization nearly complete.Quaternization of the 3- and 4-substituted pyridines does not follow the reactivity-selectivity principle, but that of 2-substituted pyridines does.The current practice of assigning detailed bimolecular structures to transition states for substitution, addition, or elimination reactions by application of the Hammond postulate is criticized in view of its inability to handle the dominating role of solvation dynamics and because of the considerable difference in potential energy content (and therefore structure) between the transition states and the reactants or products.
