1122-58-3Relevant academic research and scientific papers
Models for B12-conjugated radiopharmaceuticals. Cobaloxime binding to new fac-[Re(CO)3(Me2bipyridine)(amidine)]BF4 complexes having an exposed pyridyl nitrogen
Lewis, Nerissa A.,Marzilli, Patricia A.,Fronczek, Frank R.,Marzilli, Luigi G.
, p. 11096 - 11107 (2014)
New mononuclear amidine complexes, fac-[Re(CO)3(Me2bipy)(HNC(CH3)-(pyppz))]BF4 [(4,4′-Me2bipy (1), 5,5′-Me2bipy (2), and 6,6′-Me2bipy (3)] (bipy = 2,2′-bipyridine), were synthesized by treating the parent fac-[ReI(CO)3(Me2bipy)(CH3CN)]BF4complex with the C2-symmetrical amine 1-(4-pyridyl)piperazine (pyppzH). The axial amidine ligand has an exposed, highly basic pyridyl nitrogen. The reaction of complexes 1-3 with a B12model, (py)Co(DH)2Cl (DH = monoanion of dimethylglyoxime), in CH2Cl2 yielded the respective dinuclear complexes, namely, fac-[Re(CO)3(Me2bipy)(μ-(HNC(CH3)(pyppz)))Co-(DH)2Cl]BF4 [(4,4′-Me2bipy (4), 5,5′-Me2bipy (5), and 6,6′-Me2bipy (6)]. 1H NMR spectroscopic analysis of all compounds and single-crystal X-ray crystallographic data for 2, 3, 5, and 6 established that the amidine had only the E configuration in both the solid and solution states and that the pyridyl group is bound to Co in 4-6. Comparison of the NMR spectra of 1-3 with spectra of 4-6 reveals an unusually large wrong-way upfield shift for the pyridyl H2/6 signal for 4-6. The wrong-way H2/6 shift of (4-Xpy)Co(DH)2Cl (4-Xpy = 4-substituted pyridine) complexes increased with increasing basicity of the 4-Xpy derivative, a finding attributed to the influence of the magnetic anisotropy of the cobalt center on the shifts of the 1H NMR signals of the pyridyl protons closest to Co. Our method of employing a coordinate bond for conjugating the fac-[ReI(CO)3] core to a vitamin B12 model could be extended to natural B12derivatives. Because B12 compounds are known to accumulate in cancer cells, such an approach is a very attractive method for the development of 99mTc and 186/188Re radiopharmaceuticals for targeted tumor imaging and therapy. (Chemical Equation Presented).
N-Heteroarylphosphonates, Part II. Synthesis and reactions of 2- and 4- phosphonatoquinolines and related compounds
Haase, Mirko,Guì?nther, Wolfgang,Goì?rls, Helmar,Anders, Ernst
, p. 2071 - 2081 (1999)
We extend our synthetic method for the efficient preparation of dialkoxyphosphoryl- and phosphonio-disubstituted pyridines to include the preparation of other phosphonato substituted N-heterocycles. The key to the success of this method lies in the employment of cationic N- (trifluoromethylsulfonyl)heteroarylium triflates that are activated towards nucleophilic attack. The P(O)(OR)2 group can be transformed into the P(S)(OR)2 functionality. We report first attempts to substitute the P(O)(OR)2 moiety with C-nucleophiles. In addition to our synthetic results, the X-ray structures of two (dimethoxyphosphoryl)trifluoromethanesulfonyldihydro-N-heteroarenes are discussed. We also give complete carbon (13C) and phosphorus (31P)-NMR spectra of a series of 2- and 4-phosphonic ester substituted heteroaryl compounds and their dihydro analogs.
Continuous flow nucleophilic aromatic substitution with dimethylamine generated in situ by decomposition of DMF
Petersen, Trine P.,Larsen, Anders Foller,Ritzen, Andreas,Ulven, Trond
, p. 4190 - 4195 (2013)
A safe, practical, and scalable continuous flow protocol for the in situ generation of dimethylamine from DMF followed by nucleophilic aromatic substitution of a broad range of aromatic and heteroaromatic halides is reported.
Synthesis of aminopyridines via an unprecedented nucleophilic aromatic substitution of cyanopyridines
Penney, Jonathan M.
, p. 2667 - 2669 (2004)
The direct reaction of 2- and 4-cyanopyridines with lithium amides affords good yields of the corresponding aminopyridines via displacement of cyanide. Addition of CsF accelerates the reaction and can lead to significantly higher yields.
A Novel One-Pot Synthesis of N,N-Dimethylaminopyridines by Diazotization of Aminopyridines in Dimethylformamide in the Presence of Trifluoromethanesulfonic Acid
Filimonov, V. D.,Krasnokutskaya, E. A.,Potapova, M. I.,Sanzhiev, A. N.
, p. 1023 - 1028 (2020)
Abstract: Diazotization of aminopyridines in the presence of trifluoromethanesulfonic acid gives the corresponding pyridinyl trifluoromethanesulfonates instead of expected diazonium salts. Pyridinyl trifluoromethanesulfonates can be converted to N,N-dimethylaminopyridines on heating in dimethylformamide via replacement of the trifluoromethanesulfonyloxy group. The reaction is accelerated under microwave irradiation. A novel one-pot procedure has been proposed for the synthesis of 2- and 4-(dimethylamino)pyridines from commercially available aminopyridines. The procedure provides high yields of the target products, and it can be regarded as an alternative to the known methods of synthesis of N,N-dimethylpyridin-4-amine (DMAP) widely used as base catalyst in organic synthesis.
A simple synthesis of aminopyridines: Use of amides as amine source
Kodimuthali, Arumugam,Mungara, Anitha,Prasunamba, Padala Lakshmi,Pal, Manojit
, p. 1439 - 1445 (2010)
A transition metal/microwave irradiation (or base) free synthesis of aminopyridines has been accomplished via C-N bond forming reaction between chloropyridine and a variety of simple amides under refuxing conditions.
Mechanistic insight gained into the ligand substitution reactions of bis(o-benzosemiquinonediiminato)(triphenylphosphane)cobalt(III) - Kinetic, solvent, and volume profile studies
Alzoubi, Basam M.,Hamza, Mohamed S. A.,Duecker-Benfer, Carlos,Van Eldik, Rudi
, p. 2972 - 2978 (2003)
The ligand substitution reactions of bis(o-benzosemiquinone-diiminato)(triphenylphosphane)cobalt(III), [Co III(s-BQDI)2-(Ph3P)]+, were studied with imidazole (Imid) and 4-dimethyl-aminopyridine (4-Me2Npy) as entering nucleophiles in MeOH and CH3CN as solvents (S). The complex [CoIII(s-BQDI)2(Ph3P)S]+ undergoes dissociation of the solvent to form a five-coordinate intermediate, [Co III(s-BQDI)2(Ph3P)]+, which binds the entering nucleophile in a rate-determining step through a six-coordinate transition state, [CoIII(s-BQDI)2(Ph3P)L] +, followed by the release of triphenylphosphane to form [Co III(s-BQDI)2L]+. From the temperature and pressure dependence of the substitution of triphenylphosphane by imidazole, the activation parameters for the forward and reverse reactions of [Co III(s-BQDI)2(Ph3P)]+ with imidazole in MeOH were found to be ΔH? = 58±2 and 43.4±0.5 kJ·mol-1, ΔS? = -116±6 and -73±2 J·K-1·mo-1, and ΔV? = -10.6±0.1 and -8.7±0.3 cm3·mo-1, respectively. In CH3CN, however, ΔH?, ΔS?, and ΔV? for the forward reaction were found to be 50±3 kJ·mol-1, -111±9 J·mol-1· K-1, and -12.9±0.3 cm3·mol-1, respectively. The activation parameters for the reaction between [Co III(s-BQDI)2(Ph3P)]+ and 4-dimethylaminopyridine in MeOH for the forward and reverse reactions were found to be ΔH? = 76±2 and 47.9±0.4 kJ·mol-1, ΔS? = -51±7 and -64±2 J·K-1·mo-1, and ΔV? = -10.5±0,3 and -11.1±0.2 cm3·mo-1, respectively. From these reported rate and activation parameters, the substitution of triphenylphosphane by imidazole and 4-dimethylaminopyridine follows an associative mechanism. The ligand substitution reactions of [Co III(s-BQDI)2(Ph3P)]+ in CH 3CN were found to be faster than those in MeOH, which is attributed to the potential for hydrogen bond formation with the entering nucleophile in the case of MeOH as solvent. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Formation of Singlet Oxygen in the Deoxygenation of Heteroarene N-Oxides by Dimethyldioxirane
Adam, Waldemar,Briviba, Karlis,Duschek, Frank,Golsch, Dieter,Kiefer, Wolfgang,Sies, Helmut
, p. 1831 - 1832 (1995)
4-Dimethylaminopyridine-N-oxide 2 and 2',3',5'-triacetyladenosine-N1-oxide 4 are partially deoxygenated by dimethyldioxirane (DMD) to the corresponding amines 1 and 3; the formation of singlet oxygen suggests a polar rather than a radical mechanism, in which we propose SN2 attack of the N-oxide on the dioxirane peroxide bond.
Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
, p. 1237 - 1242 (2021/06/01)
We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
Photocatalytic deoxygenation of N-O bonds with rhenium complexes: From the reduction of nitrous oxide to pyridineN-oxides
Anthore-Dalion, Lucile,Cantat, Thibault,Kjellberg, Marianne,Nicolas, Emmanuel,Ohleier, Alexia,Thuéry, Pierre
, p. 10266 - 10272 (2021/08/12)
The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. However, the large spectrum of reduction potentials covered by nitrogen oxides makes it difficult to find general systems capable of efficiently reducing variousN-oxides. Here, photocatalysis unlocks high energy species able both to circumvent the inherent low reactivity of the greenhouse gas and oxidant N2O (E0(N2O/N2) = +1.77 Vvs.SHE), and to reduce pyridineN-oxides (E1/2(pyridineN-oxide/pyridine) = ?1.04 Vvs.SHE). The rhenium complex [Re(4,4′-tBu-bpy)(CO)3Cl] proved to be efficient in performing both reactions under ambient conditions, enabling the deoxygenation of N2O as well as synthetically relevant and functionalized pyridineN-oxides.
