Cellulose sulfuric acid is an efficient metal-free catalyst for the synthesis of 1,3,5-trisubstituted pyrazoles via the condensation of 1,3-diketones and hydrazines. The reaction was carried out in Solvent-free condition at room temperature and the products were isolated in good to excellent yields. Mild reaction conditions, as well as ease of operation and workup are some advantages of the pro...

The 1,3-Dipolar cycloaddition reactions are the classic reaction in modern synthetic organic chemistry. The concept of these reactions was introduced by Huisgen and his co-workers in the early 1960’s. 1,3-Dipolar cycloaddition reactions are simple but powerful tool for the construction of five membered heterocycles such as isoxazoles, isoxazolines, pyrazoles, pyrazolones, 1,2,4-oxadiazolines et...

The C-H amination of benzene derivatives was achieved using DDQ as photocatalyst and BocNH2 as the amine source under aerobic conditions and visible light irradiation. Electron-deficient and electron-rich benzenes react as substrates with moderate to good product yields. The amine scope of the reaction comprises Boc-amine, carbamates, pyrazoles, sulfonimides and urea. Preliminary mechanistic in...

Enaminone 1 was reacted with hydrazonoyl halides 2a-d to yield 3,4-disubstituted pyrazoles 6a-d. Coupling with arenediazonium chlorides afforded the 2-(arylhydrazono)-3-(1-naphthalenyl)-3-oxopropionaldehydes 13a-c. Compounds 13 could be utilized for the synthesis of a variety of arylpyrazoles, arylazolopyrimidines, and pyridazinones via reaction with hydrazines, aminoazoles, and active methylen...

The cyclin-dependent kinase inhibitor, CAN508, was protected with di-tert-butyl dicarbonate to access the amino-benzoylated pyrazoles. The bromo derivatives were further arylated by Suzuki-Miyaura coupling using the XPhos Pd G2 pre-catalyst. The coupling reaction provided generally the para-substituted benzoylpyrazoles in the higher yields than the meta-substituted ones. The Boc groups were onl...

The reaction of cerium(IV) ammonium nitrate (CAN) with a range of N-(p-anisyl)azoles in acetonitrile or methanol solvents leads to N-dearylation releasing the parent NH-azole and p-benzoquinone in comparable yields. The scope and limitations of the reaction are explored. It was successful with 1-(p-anisyl)pyrazoles, 2-(p-anisyl)-1,2,3-triazoles, 2-(p-anisyl)-2H-tetrazoles, and 1-(p-anisyl)penta...