86327-93-7Relevant academic research and scientific papers
Aqueous N-methylmorpholine N-oxide as a new medium for alkylation of pyrazoles
Hasratyan, Ani H.,Alexanyan, Ashkharuhi G.,Khachatryan, Hasmik N.,Zakaryan, Geghetsik B.,Hayotsyan, Sargis S.,Danagulyan, Gevorg G.,Attaryan, Hovhannes S.
, p. 751 - 754 (2018/09/19)
[Figure not available: see fulltext.] It is shown that alkylation of pyrazoles with (E)/(Z)-1,3-dichlorobut-2-enes can be carried out in an alkaline aqueous medium in the presence of N-methylmorpholine N-oxide. In some cases, this technique may substitute
Regioselective Synthesis, NMR, and Crystallographic Analysis of N1-Substituted Pyrazoles
Huang, Adrian,Wo, Kellie,Lee, So Yeun Christine,Kneitschel, Nika,Chang, Jennifer,Zhu, Kathleen,Mello, Tatsiana,Bancroft, Laura,Norman, Natalie J.,Zheng, Shao-Liang
, p. 8864 - 8872 (2017/09/11)
A systematic study of the N-substitution reactions of 3-substituted pyrazoles under basic conditions has been undertaken. Regioselective N1-alkylation, -arylation, and -heteroarylation of 3-substituted pyrazoles have been achieved using K2CO3-DMSO. The regioselectivity is justified by the DFT calculations at the B3LYP/6-31G??(d) level. A consistent steric effect on chemical shift has been observed for N-alkyl pyrazole analogues. Twenty-five X-ray crystallographic structures have been obtained to confirm the regiochemistry of the major products.
Quaternization and dequaternization of pyrazoles in solvent- free conditions: Conventional heating versus microwave irradiation
Diez-Barra, Enrique,De La Hoz, Antonio,Sanchez-Migallon, Ana,Elguero, Jose
, p. 889 - 894 (2007/10/03)
We report a study on the quaternization and dequaternization of pyrazoles by conventional heating and microwave irradiation in solvent-free conditions. Microwave irradiation produces an acceleration in the quaternization rate and a rapid equilibration between quaternized and non quaternized products. Dequaternization is also more rapid and a change on the selectivity is observed using symmetric pyrazolium salts.
Rearrangement of N-(Alkylamino)azoles in Acid Media: A New Entry to C-Amino-N-substituted Azoles
Salazar, Loreto,Espada, Modesta,Avendano, Carmen,Claramunt, Rosa Maria,Sanz, Dionisia,Elguero, Jose
, p. 1563 - 1567 (2007/10/02)
A ring-opening / ring-closure mechanism for the thermal rearrangement of 1-(alkylamino)pyrazoles into 5-amino-1-alkylpyrazoles in acid medium has been established. 1-(Benzylamino)pyrazoles show a different reactivity, affording bis(5-amino-1-benzyl-4-pyrazolyl)phenylmethanes.The reaction was extended to 1-(alkylamino)indazoles but failed in the case of 1-(alkylamino)-1,2,4-triazoles.
Activation of Exocyclic α-Positions of Azole N-Oxides by O-Silylation
Begtrup, Mikael,Vedso, Per
, p. 2555 - 2564 (2007/10/02)
Exocyclic α-positions at immonium ring carbon atoms of pyrazole and 1,2,3-triazole 1-oxides are selectively attacked in a one-pot sequence comprising silylation with iodotrimethylsilane, deprotonation with 1,2,2,6,6-pentamethylpiperidine and allylic substitution of the trimethylsilyloxy group with the iodide ions liberated by the silylation.In this way 3- and 5-iodomethylpyrazoles as well as 4-iodomethyl-1,2,3-triazoles are obtained in good yields.These may be useful for the preparation of heteroarylmethyl derivatives since the iodine atom can be displaced by even weak nucleophiles such as acetate ions.The side chain iodination is complementary to O-alkylation of the N-oxides followed by nucleophilic attack which preferentially takes place at ring carbon atoms.
Orientation de la reaction d'alkylation des pyrazoles dans des conditions neutres et en catalyse par transfert de phase
Tarrago, Georges,Ramdani, Abdelkrim,Elguero, Jose,Espada, Modesta
, p. 137 - 142 (2007/10/02)
The N-butylation and N-benzylation of nine pyrazoles bearing different substituents in positions 3 and 5 have been studied in neutral and basic medium (phase transfer catalysis).The orientation of the reaction depends strongly on the method used when the
