- Facile preparation of 3-substituted-2,6-difluoropyridines: Application to the synthesis of 2,3,6-trisubstituted pyridines
-
We report a facile method for the difluorination of 3-substituted-2,6-dichloropyridines using cesium fluoride as a fluorination reagent in dimethyl sulfoxide. It is proposed that this method for preparing 3-substituted-2,6-difluoropyridines is simpler and easier than those reported in previous literature. To examine the utility of 3-substituted-2,6-difluoropyridines in synthetic chemistry, we also demonstrate a subsequent conversion to 2,3,6-trisubstituted pyridines by a tandem nucleophilic aromatic substitution.
- Katoh, Taisuke,Tomata, Yoshihide,Tsukamoto, Tetsuya,Nakada, Yoshihisa
-
supporting information
p. 6043 - 6046
(2015/10/28)
-
- The structural proliferation of 2,6-difluoropyridine through organometallic intermediates
-
Contrary to a literature claim, 2,6-difluoropyridine-3-carboxaldehyde can be readily prepared by consecutive treatment of 2,6-difluoropyridine with lithium diisopropylamide and N,N-dimethylformamide. Regioselective displacements of fluorine from the aldehyde by nucleophiles were carried out. To demonstrate the versatility of the organometallic approach, some two dozens of further 2,6-difluoropyridine derivatives were prepared applying a combination of modern organometallic methods such as site selective hydrogen/metal and halogen/metal permutations and deprotonation-triggered heavy halogen migrations. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Schlosser, Manfred,Rausis, Thierry
-
p. 1018 - 1024
(2007/10/03)
-
- NEW DEVELOPMENTS IN THE SYNTHESIS OF LOWER FLUORINATED PYRIDINES VIA DIAZOTIZATION-FLUORINATION OF AMINOPYRIDINES IN ANHYDROUS HYDROGEN FLUORIDE
-
The isolation and stabilization of elusive 4-fluoropyridine as the hydrochloride salt (54percent yield) from fluorodediazoniation of 4-aminopyridine in anhydrous hydrogen fluoride (AHF) is described.Unlike the low yields (0-13percent) recently reported from the chlorodediazoniation of 2,6-diaminopyridine and 3-halo-2,6-diaminopyridine, fluorodediazoniation gave high yields (49-62percent) of the corresponding 2,6-difluoropyridines.In contrast, benzene analogs, i.e. m-phenylenediamine and 4-chloro-m-phenylenediamine, form only tars under similar fluorination conditions.Vicinal aminohalopyridines, e.g. 3-amino-2-chloropyridine and 2-amino-3,5-dichloropyridine give the corresponding fluorohalopyridine in 49-89percent yield.Again, the benzene analogs, i.e. o-chloroaniline and 2,4-dichloroaniline, resist fluorination.
- Boudakian, Max M.
-
p. 497 - 506
(2007/10/02)
-
- Method for preparing 2,5-dihalo- and 2,5,6-trihalopyridines
-
A method for preparing 2,5-dihalo- and 2,5,6-trihalopyridines corresponding to the formula SPC1 Wherein each X independently represents chloro, fluoro or bromo and R represents hydrogen, chloro, fluoro or bromo which comprises reacting a halohydrazinopyridine of one of the formulas SPC2 With an excess of an aqueous alkali metal hydroxide in the presence of a reaction medium from the group consisting of loweralkanols of 1 to 4 carbon atoms and loweralkylglycols of 2 to 4 carbon atoms.
- -
-
-