A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

NaOH-Assisted Multicomponent Reaction and Polymerizations of Elemental Sulfur, Diisocyanides, and Diols to Access Functional Poly(O-thiocarbamate)s

Sulfur-containing polymers with unique structures and fascinating properties have attracted much attention recently, the efficient and economic synthetic approaches for various sulfur-containing polymers have rapidly developed. Herein, the multicomponent reaction of elemental sulfur, isocyanide, and alcohol was designed at mild condition in the presence of NaOH, and the corresponding NaOH-assisted multicomponent polymerization of elemental sulfur, diisocyanides, and diols were developed at room temperature or 40 °C in air, to produce poly(O-thiocarbamate)s with well-defined structures, high molecular weights (Mws up to 32 500 g/mol) and high yields (up to 99 %). The facilely available monomers, mild condition, and high efficiency of this MCP enabled scale-up synthesis of poly(O-thiocarbamate)s, and 7.33 g polymer was obtained in 98 % yield. These functional poly(O-thiocarbamate)s could enrich Au3+ from aqueous solution with high enrichment capacity (983 mg⋅Au3+/g) and high efficiency (>99.77 %) in 1 min, demonstrating superior gold enrichment performance and their potential industrial and economic values.

Direct C-H Sulfuration: Synthesis of Disulfides, Dithiocarbamates, Xanthates, Thiocarbamates and Thiocarbonates

In light of the important biological activities and widespread applications of organic disulfides, dithiocarbamates, xanthates, thiocarbamates and thiocarbonates, the continual persuit of efficient methods for their synthesis remains crucial. Traditionally, the preparation of such compounds heavily relied on intricate multi-step syntheses and the use of highly prefunctionalized starting materials. Over the past two decades, the direct sulfuration of C-H bonds has evolved into a straightforward, atom- and step-economical method for the preparation of organosulfur compounds. This review aims to provide an up-to-date discussion on direct C-H disulfuration, dithiocarbamation, xanthylation, thiocarbamation and thiocarbonation, with a special focus on describing scopes and mechanistic aspects. Moreover, the synthetic limitations and applications of some of these methodologies, along with the key unsolved challenges to be addressed in the future are also discussed. The majority of examples covered in this review are accomplished via metal-free, photochemical or electrochemical approaches, which are in alignment with the overraching objectives of green and sustainable chemistry. This comprehensive review aims to consolidate recent advancements, providing valuable insights into the dynamic landscape of efficient and sustainable synthetic strategies for these crucial classes of organosulfur compounds.

S-alkyl Dithiocarbamates Synthesis through Electrochemical Multicomponent Reaction of Thiols, Hydrogen Sulfide, and Isocyanides

Dithiocarbamates synthesis is extremely important in plenty of biomedical and agrochemical applications, especially fungicide development, but remains a great challenge. In this work, we have successfully developed a multicomponent reaction protocol to convert H2S into S-alkyl dithiocarbamates under constant current conditions. No additional oxidants nor additional catalysts are required, and due to mild conditions, the reactions display a broad substrate scope, including varieties of thiols or disulfides.

S-Alkylation of dithiocarbamates via a hydrogen borrowing reaction strategy using alcohols as alkylating agents

Herein, we report an operationally simple, environmentally benign and scalable approach towards the synthesis of S-benzyl/alkyl dithiocarbamates via a hydrogen borrowing reaction between alcohols and dithiocarbamate anions catalyzed using a hydroxyapatite-supported copper nano-catalyst. This strategy has a broad substrate scope and offers high yields of products using inexpensive and readily available alcohols as starting materials. The catalyst was prepared by easy and straightforward methods and analyzed by several analytical techniques, e.g., FESEM, HR-TEM, BET, XRD, EDS, and XPS, demonstrating the anchoring of Cu nanoparticles on hydroxyapatite in the zero oxidation state.

Bis(μ-iodo)-tetrakis(O-methyl N-phenylthiocarbamate)-tetraiodo-dibismuth

In order to investigate the coordination chemistry of O-alkyl N-aryl thiocarbamate ligands, BiI3 was reacted with two equivalents of MeOC(=S)N(H)Ph in MeCN solution to afford the dinuclear title compound complexes [{I2Bi(μ2-I)2BiI2}{κ1-MeOC(=S)N(H)Ph}4] 1. Compound 1 was characterized by IR, UV and NMR spectroscopy, the formation of a dinuclear framework is ascertained by a single-crystal X-ray diffraction study performed at 100 K.

A stepwise one-pot synthesis of aliphatic thiols and their derivatives from acrylamides and sulfur

Elemental sulfur enables the convenient formation of C-S bonds and the direct incoporation of S-S bonds. The reactivity of easily accessible electron deficient alkenes towards sulfur, however, is barely disclosed. Herein, we investigated the reactivity of acrylamides with sulfur and eventually developed a new pseudo-multicomponent reaction for the preparation of polysulfides. Sequential one-pot reduction led to diversely substituted thiols. Additional third stage one-pot modifications provided thioethers, unsymmetric disulfide and thioester.

Assessment of Methodological Pipelines for the Determination of Isothiocyanates Derived from Natural Sources

Isothiocyanates are biologically active secondary metabolites liberated via enzymatic hydrolysis of their sulfur enriched precursors, glucosinolates, upon tissue plant disruption. The importance of this class of compounds lies in their capacity to induce anti-cancer, anti-microbial, anti-inflammatory, neuroprotective, and other bioactive properties. As such, their isolation from natural sources is of utmost importance. In this review article, an extensive examination of the various parameters (hydrolysis, extraction, and quantification) affecting the isolation of isothiocyanates from naturally-derived sources is presented. Overall, the effective isolation/extraction and quantification of isothiocyanate is strongly associated with their chemical and physicochemical properties, such as polarity-solubility as well as thermal and acidic stability. Furthermore, the successful activation of myrosinase appears to be a major factor affecting the conversion of glucosinolates into active isothiocyanates.

Synthesis of rare-earth metal complexes with a morpholine-functionalized β-diketiminato ligand and their catalytic activities towards C–O and C–N bond formation

Unusual tridentate β-diketiminato rare-earth metal chlorides LRECl(µ-Cl)2Li(THF)2 (RE = Y (1a), Yb (1b), Lu (1c); L = MeC(NDipp)CHC(Me)N(CH2)2NC4H8O; Dipp = 2,6-iPr2C6H3) and the corresponding dialkyl complexes LRE(CH2SiMe3)2 (RE = Y...

Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.

Sulfur Conversion to Multifunctional Poly(O-thiocarbamate)s through Multicomponent Polymerizations of Sulfur, Diols, and Diisocyanides

Sulfur, which is generated from the waste byproducts in the oil and gas refinery industry, is an abundant, cheap, stable, and readily available source in the world. However, the utilization of excessive amounts of sulfur is mostly limited, and developing novel methods for sulfur conversion is still a global concern. Here, we report a facile one-step conversion from elemental sulfur to functional poly(O-thiocarbamate)s through a multicomponent polymerization of sulfur, diols, and diisocyanides, which possesses a series of advantages such as mild condition (55 °C), short reaction time (1 h), 100% atom economy, and transition-metal free in the catalyst system. Seven poly(O-thiocarbamate)s are constructed with high yields (up to 95%), large molecular weight (up to 53100 of M_w), good solubility in organic solvents, and completely new polymer structures. The poly(O-thiocarbamate)s possess a high refractive index above 1.7 from 600 to 1700 nm by adjusting the sulfur content. By incorporating tetraphenylethene (TPE) moieties into the polymer structure, the poly(O-thiocarbamate)s can also be designed as fluorescent sensors to detect harmful metal cation of Hg²⁺ in a turn-on mode with high sensitivity (LOD = 32 nM) and excellent selectivity (over interference cations of Pb²⁺, Au³⁺, Ag⁺). Different from the previous reports, the exact coordination structure is first identified by single-crystal X-ray diffraction, which is revealed in a tetracoordination fashion (two sulfur and two chloride) using a model coordination compound.

A more sustainable isothiocyanate synthesis by amine catalyzed sulfurization of isocyanides with elemental sulfur

Isothiocyanates (ITCs) are typically prepared using amines and highly toxic reagents such as thiophosgene, its derivatives, or CS2. In this work, an investigation of a multicomponent reaction (MCR) using isocyanides, elemental sulfur and amines revealed that isocyanides can be converted to isothiocyanates using sulfur and catalytic amounts of amine bases, especially DBU (down to 2 mol%). This new catalytic reaction was optimized in terms of sustainability, especially considering benign solvents such as Cyrene™ or γ-butyrolactone (GBL) under moderate heating (40 °C). Purification by column chromatography was further optimized to generate less waste by maintaining high purity of the product. Thus, E-factors as low as 0.989 were achieved and the versatility of this straightforward procedure was shown by converting 20 different isocyanides under catalytic conditions, while obtaining moderate to high yields (34-95%).

Chromatography-Free Multicomponent Synthesis of Thioureas Enabled by Aqueous Solution of Elemental Sulfur

The development of a new three-component chromatography-free reaction of isocyanides, amines and elemental sulfur allowed us the straightforward synthesis of thioureas in water. Considering a large pool of organic and inorganic bases, we first optimized the preparation of aqueous polysulfide solution from elemental sulfur. Using polysulfide solution, we were able to omit the otherwise mandatory chromatography, and to isolate the crystalline products directly from the reaction mixture by a simple filtration, retaining the sulfur in the solution phase. A wide range of thioureas synthesized in this way confirmed the reasonable substrate and functional group tolerance of our protocol.