Sustainable synthesis of sulfonamides using supported ionic liquid phase catalyst containing Keggin-type anion

Unconventional approaches for the introduction of sulfur-based functional groups

Organosulfur compounds have a pivotal role in the functionalities of many natural products, pharmaceuticals and organic materials. For these reasons, the search for new methodologies for the formation of carbon-sulfur bonds has been the object of intensive work for organic chemists. However, the proposed strategies suffer from various drawbacks, such as volatility, toxicity, and instability of the sulfur sources or the use of VOC solvents. In this review, we summarise the recent protocols which have the goal of obtaining sulfones, thioethers, thiazines, thiazepines and sulfonamides in an unconventional and/or sustainable way. The use of starting materials less invasive and toxic with respect to the traditional reagents, alternative solvents such as water, ionic liquids or deep eutectic solvents, the exploitation of ultrasound and electrochemistry, increasing the efficiency of the process, are reported. Moreover, representative reaction mechanisms are also discussed.

One-pot aerobic oxidative sulfonamidation of aromatic thiols with ammonia by a dual-functional β-MnO2 nanocatalyst

High-surface-area β-MnO2 (β-MnO2-HS) nanoparticles could act as effective heterogeneous catalysts for the one-pot oxidative sulfonamidation of various aromatic and heteroaromatic thiols to the corresponding sulfonamides using molecular oxygen (O2) and ammonia (NH3) as respective oxygen and nitrogen sources, without the need for any additives.

Cellulose-Supported Ionic Liquid Phase Catalyst-Mediated Mannich Reaction

Cellulose-supported ionic liquid phase (SILP) catalyst containing a camphor sulfonate anion with a pendant ferrocenyl group was prepared and characterised with different analytical techniques such as Fourier-transform infrared, Fourier-transform Raman, and cross polarization–magic angle spinning (CP-MAS) 13C NMR spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The SILP catalyst displayed excellent catalytic activity in the synthesis of β-amino carbonyl compounds by Mannich reaction. Recycling studies revealed that SILP catalyst could be reused six times without significant decrease in catalytic activity.

Covalently anchored sulfamic acid on cellulose as heterogeneous solid acid catalyst for the synthesis of structurally symmetrical and unsymmetrical 1,4-dihydropyridine derivatives

A novel heterogeneous solid acid catalyst has been prepared by covalent grafting of chlorosulphonic acid on amino-functionalized cellulose (Cell–Pr-NHSO₃H).