Dibromination of 5‐pyrazolones and 5‐hydroxypyrazoles via dibromoisocyanuric acid

Abstract

A safe and efficient method was developed for the dibromination of pyrazolones and 5-hydroxypyrazoles by use of dibromoisocyanuric acid (DBI). The reaction gave the corresponding dibrominated pyrazolones in excellent yields (!91%).

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

“…A method for the dibromination of pyrazolones and 5-hydroxypyrazoles by the use of DBI was developed by Cheng et al The reaction gave the corresponding dibrominated pyrazolones in excellent yields. The reactions were carried out using DBI in THF as the reaction medium at room temperature (Scheme )…”

CsPbBr3 perovskite quantum dots as a visible light photocatalyst for cyclisation of diamines and amino alcohols: an efficient approach to synthesize imidazolidines, fused-imidazolidines and oxazolidines

“…However, owing to the intrinsic toxicity and handling issues of molecular bromine, an alternative bromide precursor motivated us to explore commercially available DBI which is a well-known brominating agent in organic synthesis. 51,55 Furthermore, DBI can deliver up to two bromine atoms per molecule compared to N -bromosuccinimide (NBS) 52 which is useful for the synthesis of stable CsPbBr 3 QDs under bromine-rich conditions. Literature reports show that the halide-rich surface of metal halide CsPbX 3 NCs is exceptionally stable compared to those prepared under stoichiometric conditions.…”

Pyrazole and Triazole Derivatives as Mycobacterium tuberculosis UDP-Galactopyranose Inhibitors

“…Synthesis of pyrazole derivatives MS208 and DA1-DA10 followed the synthetic route described in Scheme 1. Generally, the 1-aryl-3-methyl-5-pyrazolone (1) is synthesized via condensation between arylhydrazine and acetoacetic acid esters in a polar solvent [15,16]. Since C4 behaves as active methylene due to keto-enol tautomerism, the hydrogen of that active methylene can undergo acylation reaction [17].…”