Highly efficient synthesis of alkyl and aryl primary thiocarbamates and dithiocarbamates under metal- and solvent-free conditions

Abstract

A highly efficient, metal-free and solvent-free process is reported for the preparation of novel series of alkyl and aryl primary thiocarbamates and dithiocarbamates through the reaction of aliphatic alcohols, phenols and thiols with thiocyanate salts in the presence of 4-dodecylbenzenesulfonic acid (DBSA) as an inexpensive, readily available and amphipathic acid reagent. All reactions proceeded smoothly, and the products are obtained in good to excellent yields. Using this method, a wide range of structurally diverse primary thiocarbamates was prepared successfully.

Metal-Free Regioselective Monocyanation of Hydroxy-, Alkoxy-, and Benzyloxyarenes by Potassium Thiocyanate and Silica Sulfuric Acid as a Cyanating Agent

“…Before a precise mechanism is proposed, there is still more data to get. On the basis of all of the reported information in the literature and the above-mentioned results, the following plausible mechanism pathway can be suggested for the formation of benzonitriles derivatives (Scheme ). In the first step, isothiocyanic acid ( 5 ) will produce by the protonation of potassium thiocyanate ( 2a ) with SSA, which is in equilibrium with thiocyanic acid ( 6 ).…”

One-pot, microwave-assisted copper(i)-catalysed dithiocarbamation: facile introduction of dithiocarbamate on imidazopyridines

“…1). 7,8 The incorporation of the dithiocarbamate (DTC) unit into various biologically significant pharmacophores could serve to be important in medicinal chemistry owing to their biological diversity.…”

Nickel(II) Nanoparticles Immobilized on EDTA-Modified Fe3O4@SiO2 Nanospheres as Efficient and Recyclable Catalysts for Ligand-Free Suzuki–Miyaura Coupling of Aryl Carbamates and Sulfamates

“…Moreover, the correlation of these developments with the principles of green chemistry concepts is very necessary and important. , Concerns over contamination of residual toxic transition metals such as palladium in products and the high price of this catalyst led scientists to proliferate the use of economical and safer metal catalysts for such cross-coupling reactions. , Since the late twentieth century when the nickel-catalyzed cross-coupling reaction of aryl halides and arylboronic acids was reported by Miyaura and co-workers for the first time, this reaction has attracted a lot of attention in academic and industrial research and has become one of the most powerful synthetic tools for the C–C bond formations . Therefore, many efforts have recently been made to improve the efficiency and performance of this protocol. − One of the most important achievements of these investigations is using phenol derivatives (aryl mesylates, tosylates, triflates, phosphates, sulfamates, carbonates, or carbamates) as the proper and effective alternatives to aryl halides in the C–C bond formation reactions. − This achievement is so important because: (a) the aryl halides are generally not environmentally friendly and using such precursors produces halides as byproducts leading to environmental pollution, (b) the preparation of aryl halides often involves tedious steps, wasteful production processes, and harsh reaction conditions, and (c) the phenol derivatives are safer substrates, more accessible, and usually can be prepared on an industrial scale. − However, this reaction still suffers from several limitations and drawbacks such as the necessity to employ additional quantities of ligands such as phosphine and carbenes, the high sensitivity of these ligands toward air and moisture, having expensive and multistep procedures for the synthesis of ligands, and high catalyst loading. , …”