Unravelling the catalytic potential of a magnetic CoFe2O4/Cu–ABDC MOF composite in the sustainable synthesis of 2H-indazole motifs

A magnetic CoFe2O4/Cu–ABDC hybrid composite was fabricated for the synthesis of biologically active and pharmacologically significant 2H-indazole scaffolds.

An Operationally Simple and Efficient Synthesis of 7-Benzylidene-substitutedphenyl- 3,3a,4,5,6,7-hexahydro-2H-indazole by Grinding Method

BACKGROUND

An eco-friendly, operationally simple and efficient reaction is shown between various 2,6-bis-(substituted-benzylidene)-cyclohexanones and differently substituted hydrazine in the presence of acetic acid.

METHODS

The reaction between various 2,6-bis-(substituted-benzylidene)-cyclohexanones and differently substituted hydrazine in the presence of acetic acid afforded 7-Benzylidene-substituted-phenyl-3,3a,4,5,6,7- hexahydro-2H-indazole in 74 to 92 % yield in short reaction time using the grindstone technique.

RESULTS AND DISCUSSION

The notable advantages of this method include mild synthetic conditions, weak acid catalysis, and non-hazardous solvent which make this method environmentally safer.

CONCLUSION

In conclusion, we have developed an efficient, simple and eco-friendly method for the synthesis of 7-Benzylidene-substituted-phenyl-3,3a,4,5,6,7-hexahydro-2H-indazole by grinding technique. The notable benefits of this method are waste minimization, no organic solvent required, simple procedure, easy work-up, and clean reaction profile.

Room-Temperature, Metal-Free, and One-Pot Preparation of 2H-Indazoles through a Mills Reaction and Cyclization Sequence

The Mills reaction and cyclization of readily available 2-aminobenzyl alcohols and nitrosobenzenes using thionyl bromide provided 2H-indazoles in up to 88 % yields. In the metal-free process, acetic acid played a crucial role for the both Mills reaction and cyclization. A brominated 2H-indazole could also be obtained through the one-pot sequence.

Copper nanoparticles supported on charcoal mediated one-pot three-component synthesis of N-substituted-2H-indazoles via consecutive condensation C–N and N–N bond formation

An efficient and straightforward protocol for direct synthesis of 2H-indazoles is achieved from consecutive condensation of 2-halobenzaldehydes, primary amines, and sodium azide catalyzed by heterogeneous copper nanoparticles on charcoal (Cu/C) is achieved. The recoverable heterogeneous copper nanoparticles on charcoal (Cu/C) catalyst exhibited an impressive activity for the title reaction without any additives (expensive ligands, etc.). A series of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily accessible starting materials by employing this protocol.

Ultrasound promoted mild and facile one-pot, three component synthesis of 2H-indazoles by consecutive condensation, CN and NN bond formations catalysed by copper-doped silica cuprous sulphate (CDSCS) as an efficient heterogeneous nano-catalyst

An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an azide source in the presence of CDSCS in DMSO at room temperature furnishes 2H-indazoles in good to excellent yields. Utilizing ultrasonic irradiation techniques provided the dramatic improvements in terms of higher yields and shorter reaction times compared with conventional heating method.

Copper catalysed Ullmann type chemistry: from mechanistic aspects to modern development

Cu-catalysed arylation reactions devoted to the formation of C-C and C-heteroatom bonds (Ullmann-type couplings) have acquired great importance in the last decade. This review discusses the history and development of coupling reactions between aryl halides and various classes of nucleophiles, focusing mostly on the different mechanisms proposed through the years. Selected mechanistic investigations are treated more in depth than others. For example, evidence in favour or against radical mechanisms is discussed. Cu(I) and Cu(III) complexes involved in the Ullmann reaction and N/O selectivity in aminoalcohol arylation are discussed. A separate section has been dedicated to the synthesis of heterocyclic rings through intramolecular couplings. Finally, recent developments in green chemistry for these reactions, such as reactions in aqueous media and heterogeneous catalysis, have also been reviewed.

Cu(ii) PBS-bridged PMOs catalyzed one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles in water through click chemistry

Efficient synthesis of 1,4-disubstituted 1,2,3-triazoles using Cu(ii)-PBS-HPMO as a heterogeneous catalyst.