145162-47-6Relevant academic research and scientific papers
Regioselective Synthesis of C3-Hydroxyarylated Pyrazoles
O'Sullivan, Leonie,Patel, Ketul V.,Rowley, Ben C.,Brownsey, Duncan K.,Gorobets, Evgueni,Gelfand, Benjamin S.,Van Humbeck, Jeffrey F.,Derksen, Darren J.
supporting information, p. 846 - 854 (2021/12/27)
Pyrazoles are ubiquitous structures in medicinal chemistry. We report the first regioselective route to C3-hydroxyarylated pyrazoles obtained through reaction of pyrazole N-oxides with arynes using mild conditions. Importantly, this method does not requir
Preparation of 1-hydroxypyrazoles and 1-hydroxy-1,2,3-triazoles by dealkylation of pyrazole and triazole N-oxides
Begtrup, Mikael,Vedso, Per
, p. 549 - 555 (2007/10/03)
1-Hydroxypyrazoles were obtained from 2-benzylpyrazole 1-oxides by debenzylation with iodotrimethylsilane. 1-Hydroxy-1,2,3-triazoles were achieved from 2-benzyltriazole 1-oxides by debenzylation effected with conc. hydrobromic acid or from 2- or 3-p-methoxybenzyltriazole 1-oxides by de-p methoxybenzylation accomplished by treatment with conc. sulfuric acid. 1-Methoxy-1,2,3-triazole was obtained by de-p-methoxybenzylation of 1-methoxy-3-p-methoxybenzyl-1,2,3-triazolium tetrafluoroborate accomplished by treatment with conc. sulfuric acid. 1-Hydroxypyrazole was selectively N-benzylated in absence of base to give 2-benzylpyrazole 1-oxide which, upon selective substitution at the 3-position and subsequent debenzylation, produced 3-substituted 1-hydroxypyrazole. Acta Chemika Scandinavica 1996.
Synthesis of 4-hydroxylamino-1-azabuta-1,3-dienes and their cyclization to 2-substituted pyrazole 1-oxides
Alcazar, Jesus,Almena, Ines,Begtrup, Mikael,Hoz, Antonio de la
, p. 2773 - 2782 (2007/10/02)
2-Aromatic or 2-aliphatic substituted pyrazole 1-oxides with substituents at the 3-, 4- or 5-position have been prepared from β-dicarbonyl compounds or ketones.The β-dicarbonyl compounds were treated with p-toluidine to give 1,5-di-p-tolyl-1,5-diazapenta-1,3-dienium salts in which the p-tolyimino groups can be converted into alkylimino groups by treatment with aliphatic amine.Subsequent deprotonation and treatment with O-tert-butyldimethylsilylhydroxylamine produced 4-arylamino- or 4-alkylamino-1-tert-butyldimethylsilyloxy-1-azabuta-1,3-diene.The tautomeric structure, the configuration and the conformation of the dienes were elucidated by 1H and 13C NMR spectroscopy.Oxidation of the alkylamino-1-tert-butyldimethylsilyloxy-1-azabuta-1,3-dienes with copper(II) ions led to cyclization with formation of pyrazole 1-oxides.These could be prepared by oxidation of 3-amino oximes obtained from ketones through aminoalkylation at the α-position and treatment with hydroxyammonium chloride.If 1,5-diaryl-1,5-diazapenta-1,3-diene was treated with O-(p-tolylsulfonyl)hydroxylamine spontaneous cyclization occurred to give 1-(p-tolyl)pyrazole.
Silylation of Azole N-Oxides
Begtrup, Mikael,Vedsoe, Per
, p. 625 - 632 (2007/10/02)
Pyrazole N-oxides and 1,2,3-triazole-N-oxides can be C-silylated at ring exocyclic α-positions in high yields in a one-pot procedure by treatment with trimethylsilyl triflate, trimethylsilyl iodide or tert-butyldimethylsilyl triflate in the presence of 1,
2-Substituted Pyrazole 1-Oxides. Preparation and Reaction with Electrophilic Reagents
Begtrup, Mikael,Larsen, Peter,Vedsoe, Per
, p. 972 - 980 (2007/10/02)
1-Substituted pyrazoles have been oxidized by peracids to 2-substituted pyrazole 1-oxides.This leads to a change in reactivity towards electrophilic attack. 2-Benzylpyrazole 1-oxide is brominated, chlorinated, and nitrated selectively at C-3.The 3-halo-su
