141305-44-4Relevant academic research and scientific papers
A general synthesis of bis(o-azaheteroaryl)methane derivatives from N-oxides of azines and azoles
Szpunar, Magdalena,Loska, Rafa?
supporting information, p. 2133 - 2137 (2015/03/31)
A general method of preparation of derivatives of bis(o-azaheteroaryl)methanes from aromatic N-oxides is reported, the key step of which is a 1,3-dipolar cycloaddition between N-oxides of azines or azoles and in situ generated terminal difluoroalkenes containing an o-azaheteroaryl substituent at the double bond. Selected products were applied for the preparation of two novel unsymmetrical analogues of BODIPY fluorescent dyes, containing both an imidazole and a quinoline or isoquinoline unit.
Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles
Larionov, Oleg V.,Stephens, David,Mfuh, Adelphe M.,Arman, Hadi D.,Naumova, Anastasia S.,Chavez, Gabriel,Skenderi, Behije
, p. 3026 - 3036 (2014/05/06)
A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides.
C2, C5, and C4 azole N-oxide direct arylation including room-temperature reactions
Campeau, Louis-Charles,Bertrand-Laperle, Megan,Leclerc, Jean-Philippe,Villemure, Elisia,Gorelsky, Serge,Fagnou, Keith
, p. 3276 - 3277 (2008/10/09)
The N-oxide group imparts a dramatic increase in reactivity at all positions of the azole ring of thiazoles and imidazoles and changes the weak bias for C5 > C2 arylation to a reliable C2 > C5 > C4 reactivity profile. Use of this cross-coupling strategy enables high yielding and room-temperature C2 arylations, mild reactions at C5, and the first examples of C4 arylation-providing a unique opportunity for exhaustive functionalization of the azole core with complete control of regioselectivity. A correlation of reactivity with the relative contributions of each carbon atom to the HOMO is observed and discussed. Copyright
New Methods for the Introduction of Substituents into Thiazoles
Begtrup, Mikael,Hansen, Lars Bo L.
, p. 372 - 383 (2007/10/02)
New methods for the regioselective introduction of substituents into thiazoles have been developed using thiazole, 2-phenylthiazole and 4,5-dimethylthiazole as representative thiazoles.Improved halogenation methods, displacement of hydroxy groups in combination with dehalogenation at C-5 yield all eight possible 2-phenyl-4-halo-, 5-halo and 4,5-dihalo-thiazoles in which halogen is chlorine and bromine.Peracid oxidation of the thiazoles gives the corresponding thiazole 3-oxides.These are not activated towards halogenation but are deprotonated with sodium hydride.The anion formed react with electrophiles such as paraformaldehyde, 2,2-dimethylpropanal, 2,2-dimethylpropanoyl chloride, hexachloroethane, tetrabromomethane, and dimethyl disulfide leading to the introduction of carbon substituents, halogen, and methylthio groups.In these reactions, the reactivity of the thiazole ring positions decreases in the order 2 than 5 than 4.Monoselectivity is low when halogen and methylthio groups are introduced since these substituents enhance the acidity of adjacent ring protons. 2-Phenyl-4,5-dihalothiazole 3-oxides lose the 5-halogen when treated with sulfite ion.Trimethyloxonium tetrafluoroborate O-methylates thiazole 3-oxides.Thiazole N-oxides also react with acetyl chloride and phosphorus oxychloride to afford chlorothiazoles in a non-selective manner.Phosphorus trichloride deoxygenates thiazole 3-oxides.
