Catalyst-Free Isothiocyanatoalkylthiation of Styrenes with (Alkylthio)pyrrolidine-2,5-diones and Trimethylsilyl Isothiocyanate

Photocascade chemoselective controlling of ambident thio(seleno)cyanates with alkenes via catalyst modulation

Controlling the ambident reactivity of thiocyanates in reaction manifolds has been a long-standing and formidable challenge. We report herein a photoredox strategy for installing thiocyanates and isothiocyanates in a controlled chemoselective fashion by manipulating the ambident-SCN through catalyst modulation. The methodology allows redox-, and pot-economical 'on-demand' direct access to both hydrothiophene and pyrrolidine heterocycles from the same feedstock alkenes and bifunctional thiocyanomalonates in a photocascade sequence. Its excellent chemoselectivity profile was further expanded to access Se- and N-heterocycles by harnessing selenonitriles. Redox capability of the catalysts, which dictates the substrates to participate in a single or cascade catalytic cycle, was proposed as the key to the present chemodivergency of this process. In addition, detailed mechanistic insights are provided by a conjugation of extensive control experiments and dispersion-corrected density functional theory (DFT) calculations.

Synthesis of isothiocyanato alkyl sulfides from alkenes using KSCN and DMTSM

A method for the synthesis of isothiocyanato alkyl sulfides from KSCN and DMTSM under metal-free conditions has been developed. The features of this reaction are low-cost, readily accessible starting materials and the use of KSCN as nucleophiles for C-NCS bond formation. Alkenes with various substituted groups react smoothly and the desired products are obtained in moderate to good yields.

Isothiocyanates: happy-go-lucky reagents in organic synthesis

Owing to their unique structural features, isothiocyanates (ITCs) are a class of highly useful and inimitable reagents as the -NCS group serves both as electrophile and nucleophile in organic synthesis. ITCs share a rich legacy in organic, medicinal, and combinatorial chemistry. Compared to their oxygen equivalents, isocyanates, ITCs are easily available, less unpleasant, and somewhat less harmful to work with (mild conditions) which makes them happy-go-lucky reagents. Functionalized ITCs can finely tune the reactivity of the -NCS group and thus can be exploited in the late-stage functionalization processes. This review's primary aim is to outline ITC chemistry in the construction and derivatization of heterocycles through the lens of sustainability. For ease and brevity, the sections are divided based on reactive centers present in functionalized ITCs and modes of cyclisation. Scrutinizing their probable unexplored directions for future research studies is also addressed.

Recent advancement in the synthesis of isothiocyanates

Isothiocyanates exhibit various biological characteristics, including antimicrobial, anti-inflammatory, and anticancer properties. Their significance extends to synthetic chemistry, where they serve as valuable platforms for versatile transformations. Consequently, they have attracted the attention of biologists and chemists. This review summarizes recent advancements in the synthesis of isothiocyanates. Access to a variety of starting materials is important to prepare isothiocyanates with diverse structures. This review categorizes synthetic methods into three types based on the starting materials and functional groups: (i) type A, derived from primary amines; (ii) type B, derived from other nitrogen functional groups; and (iii) type C, derived from non-nitrogen groups. Recent trends in synthetic methods have revealed the prevalence of type-A reactions derived from primary amines. However, type B reactions have rarely been reported. Notably, over the past four years, there has been a notable increase in type C reactions, indicating a growing interest in non-nitrogen-derived isothiocyanates. Overall, this review not only outlines the advancements in the synthesis of isothiocyanates but also highlights trends in the methodology.

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

In the field of organosulfur chemistry, sulfenylating agents are an important key in C-S bond formation strategies. Among various organosulfur precursors, N-sulfenylsuccinimide/phthalimide derivatives have shown highly electrophilic reactivity for the asymmetric synthesis of many organic compounds. Hence, in this review article, we focus on the application of these alternative sulfenylating reagents in organic transformations.

Lewis Acid-Mediated Electrophilic Thiolative Difunctionalization of Enimides: Rapid Access to β-Amino Sulfides

An efficient and practical route for the synthesis of β-amino sulfides by Lewis acid-mediated electrophilic thiolative difunctionalization of enimides is disclosed. A series of free phenols, electron-rich arene, alcohol, azide, and hydride, are successfully incorporated into the substrates in high regio- and stereoselectivities under mild conditions. The obtained products possess multiple functional groups and can be easily transformed to other valuable molecules.

Recent advances in thiolation via sulfur electrophiles

This review systematically summarizes the recent developments for constructing sulfur compounds from sulfur electrophiles, and the mechanism mainly involved thirranium ions, sulfur ylides, C–S cross coupling and electrophilic substitution.

BF3·OEt2-mediated cyclization of β,γ-unsaturated oximes and hydrazones with N-(arylthio/arylseleno)succinimides: an efficient approach to synthesize isoxazoles or dihydropyrazoles

A highly efficient BF3·OEt2-mediated cyclization of β,γ-unsaturated oximes and tosylhydrazones with N-(arylthio/arylseleno)succinimides has been established for the construction of N-heterocycles in a one-step manner. This metal-free cyclization provides direct access to isoxazoles and dihydropyrazoles in good to excellent yields at room temperature. The mechanistic experiments support the formation of a cationic species PhS+ which plays a critical role in this cyclization process.

Intermolecular sulfenoamination of alkenes with sulfonamides and N-sulfanylsuccinimides to access β-sulfonylamino sulfides and dihydrobenzothiazines

An acid-catalyzed intermolecular sulfenoamination of alkenes is developed with sulfonylamides as the N-source, enabling the synthesis of β-sulfonylamino sulfides and dihydrobenzothiazines.