Homogeneous and Nanoparticle Gold-Catalyzed Hydrothiocyanation of Haloalkynes

Oxidant- and Base-Free, Copper-Catalyzed Difluoromethylation of Haloalkynes

We report herein a highly efficient copper-catalyzed protocol for the transformation of haloalkynes to the corresponding difluoromethylated alkynes. This scalable protocol exhibits a broad substrate scope and excellent functional group tolerance, enabling the late-stage difluoromethylation of bioactive molecules. Additionally, the strategy of utilizing the difluoromethylalkynes in gram-scale reactions and multiple transformations has proven to be highly valuable in synthetic chemistry.

Tracking the Growth of Chiral Plasmonic Nanocrystals at Molybdenum Disulfide Heterostructural Interfaces

The way of accurately regulating the growth of chiral plasmonics is of great importance for exploring the chirality information and improving its potential values. Herein, cysteine enantiomers modulate the anisotropic and epitaxial growth of gold nanoplasmonics on seeds of exfoliated MoS₂ nanosheets. The heterostructural Au and MoS₂ hybrids induced by enantiomeric cysteine are presented with chiroptical characteristics, dendritic morphologies, and plasmonic performances. Moreover, the synthesis, condition optimization, formation mechanism, and plasmonic properties of Au and MoS₂ dendritic nanostructures are studied. The chirality characteristics are identified using the circular dichroism spectra and scanning electron microscopy. Time-resolved transmission electron microscopy and UV-vis spectra of the intermediate products captured are analyzed to confirm the formation mechanism of dendritic plasmonic nanostructures at heterostructural surfaces. The specific dendritic morphologies originate from the synergistic impacts of heterostructural MoS₂ interfaces and enantiomeric cysteine-induced anisotropic manipulation. Significantly, the developed synthesis strategy of chiral nanostructures at heterostructural interfaces is highly promising in promoting the understanding of the plasmonic function and crucial chirality bioinformation.

Transition-metal-free Synthesis of tetra-substituted Vinyl Iodides by Cascade Sequential Reaction of α-Keto Acids, 1-Iodoalkynes, and Alkyl Halides

The cascade sequential reaction of α-keto acids, 1-iodoalkynes, and alkyl halides are reported herein to synthesize tetra-substituted vinyl iodides. It represents an efficient protocol to access a diverse range of tetra-substituted vinyl iodides starting from simple materials in a one-pot fashion, featuring mild reaction conditions, ease of operation, and broad substrate scope.

Iodine-Promoted Oxidative Cyclization of Methyl Azaarenes and α-Amino Ketones for One-Pot Synthesis of 2-Azaaryl-5-aryl Oxazoles

A high efficiency protocol was developed for the synthesis of 2,5-disubstituted oxazoles via iodine-promoted oxidative domino cyclization. These reactions were performed with readily available methyl azaarenes and α-amino ketones under metal-free conditions. This protocol is a simple method with high functional group compatibility, a wide range of substrates, and excellent yield, providing a new way to synthesize azaarene-attached oxazoles.

Palladium-catalyzed oxidative C-H activation/annulation of N-alkylanilines with bromoalkynes: access to functionalized 3-bromoindoles

A straightforward approach to the synthesis of 3-bromoindoles via palladium-catalyzed oxidative C-H activation/annulation of N-alkylanilines with bromoalkynes has been described. This protocol features high atom economy, excellent chemo- and regioselectivities, and good functional group tolerance. Moreover, the resultant 3-bromoindoles can be transformed to various functionalized indole derivatives, which demonstrates the practicability of this method in organic synthesis.

Recent progress of direct thiocyanation reactions

Thiocyanates are common in natural products, synthetic drugs and bioactive molecules. Many thiocyanate derivatives show excellent antibacterial, antiparasitic and anticancer activities. Thiocyanation can introduce SCN groups into parent molecules for constructing SCN-containing small organic molecules. Among them, the direct introduction method mainly includes nucleophilic reaction, electrophilic reaction and free radical reaction, which can simply and quickly introduce SCN groups at the target sites to construct thiocyanates, and has broad application prospects. In this review, we summarize the research progress of direct thiocyanation in recent years.

Gold(I)-Catalyzed Selective Hydroarylation of Indoles with Haloalkynes

A highly regio- and stereoselective synthesis of a Z-alkenyl indole via the gold-catalyzed addition of an indole to a haloalkyne was developed. In the presence of gold catalyst SIPrAuCl and cocatalyst NaBARF, a broad range of indoles react with haloalkynes to afford Z-alkenyl indoles with high selectivity at room temperature. Computational studies suggest that the hydroarylation reaction takes place via a concerted C2 addition pathway of the indole to the activated haloalkyne.

Recent advances in photochemical and electrochemically induced thiocyanation: a greener approach for SCN-containing compound formation

Techniques utilizing photo- and electrochemically induced reactions have been developed to accelerate organic processes. These techniques use light or electrical energy (electron transfer) as a direct energy source without using an initiator or reagent. Thiocyanates are found in biologically active and pharmacological compounds and can be converted into various functional groups. It is one of the most prominent organic scaffolds. Significant development in photo- and electro-chemically induced thiocyanation procedures has been made in recent years for the conception of carbon-sulfur bonds and synthesis of pharmaceutically important molecules. This review discusses different photo- and electro-chemically driven thiocyanation C(sp³)–SCN, C(sp²)–SCN, and C(sp)–SCN bond conception processes that may be useful to green organothiocyanate synthesis. We focus on the synthetic and mechanistic characteristics of organic photo- and electrochemically accelerated C–SCN bond formation thiocyanation reactions to highlight major advances in this novel green and sustainable research field.

Techniques utilizing photo- and electrochemically induced reactions have been developed to accelerate organic processes.

Recyclable Gold Catalyst for the Stereoselective Thioallylation of Alkynes

The heterogeneous gold(I)-catalyzed stereoselective thioallylation of electron-deficient alkynes with allyl sulfides has been achieved by using an MCM-41-immobilized sterically demanding NHC-gold(I) complex [MCM-41-IPrAuNTf₂] as the catalyst under mild conditions, delivering a wide variety of stereodefined tri- and tetrasubstituted functionalized vinyl sulfides in good to excellent yields. The new heterogeneous MCM-41-IPrAuNTf₂ catalyst exhibits an activity comparable to a homogeneous IPrAuNTf₂ complex and can be recovered via a simple filtration process and reused for at least seven consecutive cycles without any apparent loss of its catalytic activity and selectivity.

The simplest alkynyl thiocyanate HCCSCN and its isomers

The simplest alkynyl thiocyanate HCCSCN has been synthesized and characterized for the first time. HCCSCN is surprisingly stable at room temperature but undergoes photoisomerization in an Ar-matrix (10 K) to yield the novel sulfenyl isocyanide HCCSNC and thioketene NCC(H)CS. The isomeric isothiocyanate HCCNCS, missing in the photochemistry of HCCSCN, can be generated through the photodecarbonylation of propiolyl isothiocyanate.

Design and Use of Electrophilic Thiocyanating and Selenocyanating Reagents: An Interesting Trend for the Construction of SCN- and SeCN-Containing Compounds

Organothiocyanate and organoselenocyanate compounds are of paramount importance in organic chemistry as they are key intermediates to access sulfur- and selenium-containing compounds. Therefore, among the different synthetic pathways to get SCN- and SeCN-containing molecules, original methodologies using electrophilic reagents have recently been explored. This Minireview will showcase the recent advances that have been made. In particular, the design of several electrophilic sources and their applications for the thiocyanation and the selenocyanation of various classes of compounds will be highlighted and discussed.

Lewis Base/Brønsted Acid Cocatalysis for Thiocyanation of Amides and Thioamides

Lewis base/Brønsted acid cocatalysis for electrophilic thiocyanation of olefins is reported. Using a combination of triphenylphosphine selenide and diphenyl phosphate as a catalyst, a wide range of unsaturated amides and thioamides underwent thiocyanation to furnish thiocyanated thiazoline and oxazoline derivatives in high yields (up to 97%).

Efficient synthesis of 1-iodoalkynes via Al2O3 mediated reaction of terminal alkynes and N-iodosuccinimide

Iodination of terminal alkynes using N-iodosuccinimide (NIS) in the presence of γ-Al₂O₃ was developed to afford 1-iodoalkynes with good to excellent yields (up to 99%). This described approach featured excellent chemoselectivity, good functional group tolerance, and utilization of an inexpensive catalyst.

An efficient Al₂O₃-mediated direct iodination of terminal alkynes was developed to afford 1-iodoalkynes.

Regio- and stereoselective thiocyanatothiolation of alkynes and alkenes by using NH4SCN and N-thiosuccinimides

A highly regioselective thiocyanatothiolation of alkynes and alkenes assisted by hydrogen bonding under simple and mild conditions is developed. Our thiocyanatothiolation reagents are readily available ammonium thiocyanate and N-thiosuccinimides. This metal-free system offers good chemical yields for a wide range of alkyne and alkene substrates with good functional group tolerance.

A highly regioselective thiocyanatothiolation of alkynes assisted by hydrogen bonding under simple and mild conditions is developed.

Access to SCN-containing thiazolines via electrochemical regioselective thiocyanothiocyclization of N-allylthioamides

An electrochemical thiocyclization of N-allylthioamides has been developed for the synthesis of SCN-containing 2-thiazolines and NCS-containing thiazines.

Lewis-Acid-Mediated Thiocyano Semipinacol Rearrangement of Allylic Alcohols for Construction of α-Quaternary Center β-Thiocyano Carbonyls

An electrophilic thiocyano semipinacol rearrangement of allylic alcohols has been achieved for the first time by using N-thiocyano-dibenzenesulfonimide (NTSI). This approach provides a direct, simple, and efficient strategy for the formation of thiocyano carbonyl compounds with moderate to excellent yields. Meanwhile, an all-carbon quaternary center was rapidly constructed. In addition, an asymmetric version of this tandem reaction was preliminarily investigated.

TMSCl-Catalyzed Electrophilic Thiocyano Oxyfunctionalization of Alkenes Using N-Thiocyano-dibenzenesulfonimide

Numerous electrophilic thiocyano oxyfunctionalization reactions of alkenes have been achieved using N-thiocyano-dibenzenesulfonimide, which is a new electrophilic thiocyanation reagent and could be easily prepared in two steps from dibenzenesulfonimide. This approach provides efficient, simple, and modular methods for the formation of SCN-containing heterocycles such as lactones, tetrahydrofurans, dihydrofurans, and dihydrobenzofurans in moderate to excellent yields. Meanwhile, diverse oxa-quaternary centers were rapidly constructed. Additionally, this protocol is free of transition metals and features broad substrate toleraance and mild reaction conditions.

Copper-catalyzed cascade click/nucleophilic substitution reaction to access fully substituted triazolyl-organosulfurs

A novel cascade click/nucleophilic substitution reaction is developed to access various 4-heterofunctionalized fully substituted triazolyl-organosulfurs.