1457-42-7

Usage

Uses

Coupling partner in Pd-catalyzed direct arylation reactions.

Purification Methods

Purify the oxide by distillation in a vacuum and by sublimation in vacuo. When a solution of the oxide in MeOH is treated with an aqueous solution of CuCl2, the [C4H4N2O]2—CuCl2-2H2O-complex (m 182-183o) is formed from which the oxide can be recovered . [Pollak et al. J Org Chem 35 2478 1970, Klinge et al. Recl Trav Chim, Pays Bas 95 21 1976, Ohsawa et al. Tetrahedron Lett 1979 1978, Koelsch & Gumprecht J Org Chem 23 1605 1958, Beilstein 23 III/IV 890.]

InChI:InChI=1/C4H4N2O/c7-6-4-2-1-3-5-6/h1-4H

Upstream product

• 289-80-5 1,2-diazine 
• 71246-74-7 4-(3-cyano-1-triazeno)pyridazine 1-oxide potassium salt 

Downstream Products

• 1608-03-3 (E)-but-1-en-3-yn-1-ylbenzene 
• 23517-07-9 ((E)-1-(but-1-en-3-yn-1-yl)-4-methoxybenzene) 
• 72450-95-4 (E)-1-(m-Chlorphenyl)but-1-en-3-in 
• 23517-08-0 (E)-1-(but-1-en-3-yn-1-yl)-2-methoxybenzene 
• 23517-06-8 (E)-1-(but-1-en-3-yn-1-yl)-3-methylbenzene 
• 23517-04-6 (E)-1-(but-1-en-3-yn-1-yl)-4-methylbenzene 
• 23517-05-7 (E)-1-(but-1-en-3-yn-1-yl)-2-methylbenzene 
• 19883-27-3 (3E,5Z)-1,3,5-undecatriene 
• 16356-11-9 (3E,5E)-1,3,5-undecatriene 
• 85615-64-1 undecatriene-2Z,4Z,6E 
• 132643-65-3 9-Oxa-2-aza-benzocycloheptene 
• 132643-66-4 5-Oxa-2-aza-benzocycloheptene 
• 108563-78-6 9-Oxa-1-aza-benzocycloheptene 
• 51447-08-6 (1,3Z,5E)-undeca-1,3,5-triene 

Relevant academic research and scientific papers

NMR Studies of Pyridazine-N-Oxide. Determination of Spectroscopic Parameters from the - and Parent Species

Pyridazine-N-oxide and pyridazine-N-oxide have been investigated by NMR spectroscopy. 1H and 13C spectra have been obtained and analyzed, in terms of chemical shifts and spin-spin coupling constants.Relaxation times have been measured for 13C and have been used to determine the correlation time τc under the assumption of isotropic molecular diffusion.From 1H, 15N INDOR experiments the lineshape of N(2) is determined: analysis of the lineshape yields 1JNN and TqN(1).On the basis of experimental data and observed linewidth variations, the N(1) nitrogen quadrupole coupling constants has been evaluated.The experimental data are correlated with semiempirical calculations within the azine series.

Experimental and theoretical molecular and electronic structures of the N-oxides of pyridazine, pyrimidine and pyrazine

The structures of pyridazine N-oxide, pyrimidine N-oxide and pyrazine N-oxide have been determined by X-ray diffraction for the first time. Comparison with theoretical predictions of the equilibrium structures using the B3LYP method together with a cc-pVTZ basis set, show close agreement with the structural parameters observed, and experimental dipole moments, which suggests that the charge distribution is realistic. An 'atoms in molecules' (AIM) analysis of the computed wave-functions shows total electron densities rather different from the classical picture of a dative bond, whereas the same wave-functions subjected to Mulliken analysis show a more conventional view of the electron distribution. This latter procedure allows a bond dipole analysis of the N-oxide charge distribution.

Strategic Approach on N-Oxides in Gold Catalysis – A Case Study

An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).

Pd-Catalyzed Direct C-H Alkenylation and Allylation of Azine N -Oxides

A Pd-catalyzed direct C2-alkenylation of azine N-oxides with allyl acetate is disclosed. The products are formed through an allylation/isomerization cascade process. The use of a tri-tert-butylphosphonium salt as the ligand precursor and KF is mandatory for optimal yields. When cinnamyl acetate is used, the same catalytic system promotes C2-cinnamylation of the azine N-oxide without subsequent isomerization. A mechanism is proposed on the basis of experimental studies and DFT calculations.

Synthesis of N,N-Dioxopyridazines

Despite many efforts, one of the smallest heterocycles containing two nitrogen atoms, pyridazine, could not be converted to its N,N-dioxide (see, however, Nakadate et al. Chem. Pharm. Bull. 1970, 18, 1211-1218). HOF·CH3CN, made easily from diluted fluorine, was able to accomplish this task in a fast reaction with good yields.

Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts

We report the first reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%). N-Methoxy imidazolium salts are accessible in three steps from commercial amines (50-85%). In total 36 discrete methoxyheteroarenium salts bearing electron-donating, electron-withdrawing, alkyl, aryl, halogen, and haloalkyl substituents were prepared (several in multigram quantities) and coupled with 38 different alkenes. The transformations proceed under neutral conditions at ambient temperature, provide monoalkylation products exclusively, and form a single alkene addition regioisomer. Preparatively useful and complementary site selectivities in the addition of secondary and tertiary radicals to pyidinium salts are documented: harder secondary radicals favor C-2 addition (2->10:1), while softer tertiary radicals favor bond formation to C-4 (4.7->29:1). A diene possessing a 1,2-disubstituted and 2,2-disubstituted alkene undergoes hydropyridylation at the latter exclusively (61%) suggesting useful site selectivities can be obtained in polyene substrates. The methoxypyridinium salts can also be employed in dehydrogenative arylation, borono-Minisci, and tandem arylation processes. Mechanistic studies support the involvement of a radical process.

Pyridazine N-Oxides as Precursors of Metallocarbenes: Rhodium-Catalyzed Transannulation with Pyrroles

Pyridazine N-oxides are used for the first time as precursors of metallocarbenes. These nitrogen-rich heterocycles led to the discovery of a novel acceptor and donor-acceptor enalcarbenoids. The synthetic utility of these metallocarbenes was demonstrated in the rhodium-catalyzed denitrogenative transannulation of pyridazine N-oxides with pyrroles to the valuable alkyl, 7-aryl, and 7-styryl indoles. The transannulation strategy was applied to the synthesis of a potent anticancer agent.

Use of N-oxide compounds in coupling reactions

Metal-catalyzed coupling process comprising reacting a compound of general formula 1 with a compound A-X, to obtain a compound of general formula 2, which may further be converted to a compound of general formula 3

Palladium-catalyzed cross-coupling reactions of diazine N-oxides with aryl chlorides, bromides, and iodides

New aspects of N-oxides: Pyrazine, pyridazine, and pyrimidine N-oxides are regioselectively arylated with aryl iodides, bromides, and chlorides in the presence of a palladium catalyst (see scheme). The resulting products can be deoxygenated in high yield

Reactivity of perfluoro-(cis-2,3-dialkyloxaziridines) with heteroaromatic nitrogen compounds

Pyridine N-oxides 3 are exclusively formed under particularly mild conditions when perfluorinated dialkyloxaziridines 1 are reacted with pyridine derivatives 2 bearing a substituent at the 2-position. Starting from pyridines substituted at the 3- and 4-positions, the previously unreported N-perfluoroacylpyridiniumaminides 4 are also produced and isolated as solid, stable compounds. Bis(pyridinium-N-aminides) 9, which have been prepared starting from bis-pyridine substrates and pyridazine and quinoxaline starting materials, also show the same reactivity. This behaviour reveals how oxaziridines 1 can work as both animating and oxygenating agents.