Copper-Catalyzed Oxidative Thioamination of Maleimides with Amines and Bunte Salts

Easy Access to α-Ketothioamides via Oxidative Amidation of Bunte Salts Using Electrolysis or Hypervalent Iodine

Two new protocols leveraging electrochemical and hypervalent iodine-mediated synthesis of α-ketothioamides have been developed by using easily accessible and cost-effective Bunte salts and secondary amines. The methods are efficient, simple, and straightforward, and showcase the formation of C-N bonds across diverse substrates under ambient conditions.

A Method for the Synthesis of Thioindoles through Copper-Catalyzed C-S Bond Coupling Reaction

We herein report the copper-catalyzed C-S bond coupling reaction of indoles with N-thiosuccinimides, resulting in moderate to excellent yields of mono- and bis-sulfenylated compounds such as arylthioindoles, alkylthioindoles, selenylated indoles, and cysteine-substituted indoles. Thioarylation and thioglycosylation at the C2 position of indole alkaloids in the Radix Isatidis were achieved via structural modification. The first total syntheses of isatindigotindolosides III and IV have been successfully carried out. The electrophilic sulfenyl bromides generated in situ can play an important role in the catalytic cycle.

Divergent Trideuteromethylthiolation and Aminotrideuteromethylthiolation of Alkenes with N-Fluorobenzenesulfonimide and CD3SSO3Na

A metal-free oxidative trideuteromethylthiolation of alkenes with CD3SSO3Na using NFSI as an oxidant has been developed. The aminotrideuteromethylthiolation of a three-component reaction could be easily achieved in the presence of a cobalt catalyst. The divergent trideuteromethylthiolation of alkenes, readily available trideuteromethylthiolation reagent, and versatile synthetic strategy allow for late-stage modification of drug molecules.

Photo-induced 1,2-thiohydroxylation of maleimide involving disulfide and singlet oxygen

A visible light-driven di-functionalization of maleimide with disulfide and in situ-generated singlet oxygen offers selective 1,2-thiohydroxylation under additive-free conditions. Here the disulfide plays the dual role of photosensitizer and the coupling reagent. Notably, the hydroxyl functionality originates from the in situ generated singlet oxygen followed by HAT from H2O (moisture).

Transition-Metal-Free Base-Promoted Deaminative Coupling of Gramines with Aminomaleimides

The direct utilization of amines for C-C bond formation without prefunctionalization remains a significant challenge. Herein, we report the base-promoted deaminative coupling of gramines with aminomalaimides under redox-neutral conditions. In this operationally simple reaction, a series of indolmethyl-substituted aminomaleimides that emitted fluorescence were synthesized in good-to-excellent yields. Biological evaluation revealed that some products exhibited antiproliferative activity against human cancer cell lines.

Alkyltin fluorides as alkylating reagent in aminoalkylation of maleimides

Alkyltin fluoride is a frequently used electrophilic stannylation reagent via the cleavage of the Sn-F bond in traditional organic synthetic chemistry. Herein, we report the unprecedented copper-catalyzed aminoalkylation of maleimides using alkyltin fluoride as alkylating reagent through cleavage of the C-Sn bond via a radical pathway. Excellent functional group tolerance, use of O₂ as green oxidant and late-stage modification of some drug intermediates are the standout features of the current toolbox. Mechanistic studies reveal that alkyltin fluorides are capable of producing alkyl radicals in a Cu/O₂ catalytic system.

Palladium-Catalyzed N-Alkenylation of N-Aryl Phosphoramidates with Alkenes

Versatile and concise Pd-catalyzed oxidative N-alkenylation of N-aryl phosphoramidates with alkenes is described in this study, a reaction that is of great significance but surprisingly unexploited. The transformation proceeds under mild reaction conditions, using O₂ as a green oxidant and TBAB as an effective additive. An efficient catalytic system allows a variety of drug-related substrates to participate in these transformations, which is of great interest in the drug discovery and development of phosphoramidates.

Direct methylthiolation of C-, S-, and P-nucleophiles with sodium S-methyl thiosulfate

A practical and efficient methylthiolation that employed the typical Bunte salt sodium S-methyl sulfothioate as the sulfur source was described. This reagent could react with a variety of compounds such as alkynes, 1,3-diketones, thiols, selenol and H-phosphine oxides, affording methylthiolated products in moderate to excellent yields. The advantages such as easy preparation, air- and moisture-stability and high tolerance of functional groups demonstrated the potential of this reagent to be widely applied in organic synthesis. Notably, the robustness of this reagent was demonstrated by the late-stage modification of drug molecules of erlotinib.

Copper-Catalyzed C2- or C3-Thioglycosylation of Indoles with N-(Thioglycosides)succinimides: An Effective Strategy for the Total Synthesis of Isatindigotindolosides

Isatindigotindolosides, indoles containing a 1-S-β-glucopyranosyl unit at position C2, show promising bioactivity. Here, we report a copper-catalyzed C2- or C3-thioglycosylation of indoles with N-(thioglycosides)succinimides to construct indole alkaloid glucosides. This reaction is widely tolerant of functional groups, as various indoles and thioglycosides are suitable. It also provides a reliable method for performing late-stage modifications of natural products, such as gramine and melatonin. Total syntheses of isatindigotindolosides I and II were successfully accomplished using the C2-thioglycosylation reaction as a key step.

The copper-catalyzed radical aminophosphinoylation of maleimides with anilines and diarylphosphine oxides

The radical aminophosphinoylation of maleimides with anilines and diarylphosphine oxides.

Ag-Cu copromoted direct C2-H bond thiolation of azoles with Bunte salts as sulfur sources

A direct C2-H thiolation of azoles with Bunte salts was achieved under the combined action of copper and silver salts. This protocol could furnish various substituted 2-thioazoles in moderate to good yields. This method has a broad substrate scope and shows good functional group tolerance.

Amine hydrochloride salts as bifunctional reagents for the radical aminochlorination of maleimides

Amine hydrochloride salts have been typically used as amination reagents.

Iodine-catalyzed thioallylation of indoles using Bunte salts prepared from Baylis-Hillman bromides

Metal-free iodine-catalyzed regioselective thioallylation of indoles has been accomplished at room temperature using Bunte salts prepared from Baylis-Hillman bromides. The resulting multi-functional C3 thioallylated indoles exhibit ample structural diversity and good functional group tolerance.

An MeSeSO3Na reagent for oxidative aminoselenomethylation of maleimides

Herein, we describe the design and synthesis of an MeSeSO3Na reagent, which proved to be a versatile selenomethylation reagent for copper-catalyzed aminoselenomethylation of maleimides.

Synthetic developments on the preparation of sulfides from thiol-free reagents

This critical review covers the main thiolating reagents with respect to their characteristics and reactivities. In fact, they are complementary to each other and bring different thiolation strategies, avoiding the hazardous thiol derivatives.