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A visible-light-enabled, photocatalyst-free conjugate addition reaction of dehydroamino acids is disclosed. Employing 4-acyl-1,4-dihydropyridines as both a radical reservoir and reductant, various β-acyl α-amino acids and their deuterated analogues were obtained in good results. Both late-stage peptide modification and stereoselective synthesis of chiral oxazolidinones are successfully achieved. The protocol is characterized by mild conditions and efficient derivatization, thus unlocking a novel blueprint to access unnatural amino acid derivatives, important building blocks with potential application in the peptidomimetic toolbox.

Reported herein is the first example of electrochemical selenocyanation of imidazo[1,5-a]quinolines with KSeCN under metal catalyst- and chemical oxidant-free conditions. This sustainable strategy shows a broad scope and great compatibility with functional groups, and affords synthetically and biologically important selenocyanated imidazo[1,5-a]quinolines in good to excellent yields with cheap graphite and Ni plates as the electrodes. The gram-scale synthesis was also successfully conducted, which might demonstrate the potential value of this electrochemical protocol.

Herein, we report a Pd-catalyzed mono-α-arylation reaction for pyridine benzylic functionalization. This approach serves as an efficient alternative to synthesize di-heteroaryl acetates in good yields and selectivities. Moreover, the method is applicable to heteroaryl substrate combinations, and exhibits great functional group tolerance. A streamlined protocol also enables the rapid synthesis of diheteroaryl ketones. The synthetic value was also demonstrated by scale-up experiments

A platform approach for the direct synthesis of 3-substituted 2H-indazole derivatives has been developed using a Ag(I)/Na2S2O8 system. This regioselective alkylation/acylation protocol operates under mild conditions, tolerates a wide range of structural moieties and delivers versatile 2H-indazole derivatives with high efficiency. The gram-scale reaction and the application to the synthesis of bioactive molecules further demonstrate the utility of our protocol.

Aziridines are ubiquitous in bioactive molecules and often serve as key synthetic building blocks. We report herein an intramolecular KI/TBHP mediated oxidative dehydrogenative C(sp3)–H amination reaction to synthesize a diverse array of trans-2,3-disubstituted aziridines in good yields under mild conditions. The synthetic utility of this protocol was further highlighted by a one-pot, two-step synthesis of unprotected aziridines.

Herein, we report a highly efficient ZnI2 -triggered oxidative cross-coupling reaction of P(O)-H compounds and amines. This operationally simple protocol provides unprecedented generic access to phosphinic amides/phosphoramidate derivatives in good yields and short reaction time. Besides, the reaction proceeds under mild conditions, which avoids the use of hazardous reagents, and is applicable to scale-up syntheses as well as late-stage functionalization of drug molecules. The stereospecific coupling is also achieved from readily available optically enriched P(O)-H compounds.

An electrochemical oxidative dehydrogenative C(sp3)–H amination reaction to construct trans-2,3-disubstituted aziridines is reported, which avoids using external oxidants and generates only hydroge...

Herein we report a protocol for the visible-light-mediated alkylation/acylation reaction of benzothiazoles. Alkyl/acyl substituted Hantzsch esters are easily prepared and rationally used as radical precursors. In the presence of BF3·Et2O and Na2S2O8, various benzothiazole derivatives were readily obtained in good yields. Our user-friendly protocol can proceed by simple irradiation with blue LEDs (λ = 465 nm) and without the assistance of external photocatalysts. The reaction is also characterized by mild conditions and scalability, thus offering an alternative and efficient tool for the synthesis of 2-functionalized benzothiazoles.

The efficient synthesis of 2-substituted thiazoles and benzothiazoles has been accomplished employing readily available cysteine esters and 2-aminobenzenethiols as N and S sources. The reaction proceeds under an I2/TBHP system and involves a one-pot tandem cyclization and oxidation sequence. A diverse range of aldehydes is amenable for this transition-metal-free protocol, which provides an alternative method to rapidly access thiazole-containing molecules.

Organosulfur compounds are ubiquitous in natural products and active pharmaceutical ingredients. They are also versatile scaffold that are widely applicable in material and food chemistry. The increasing demand indeed lead to a continuous progress in developing of new methodologies in organosulfur chemistry. Among them, sulfur ylides and sulfonium salts with unique reactivities have been employed to provide simple, effective, and often stereoselective methods to gain access to sulfur containing molecules. The essential goal of this review is to provide a comprehensive account of representative research progress on sulfonium salt and sulfur ylide chemistry in the past three years. Seminal reports on this topic are occasionally covered with the purpose of providing a brief research background. For the sake of convenience, this review is organized in three parts based on the role they played in organic reactions (synthetic intermediates, reagents and catalysts). In the first section, the development of new approaches for generate sulfur ylide or sulfonium salt intermediates were summarized. Electrophilic aryne species could be employed to react with sulfides or sulfoxides to form the desired sulfur intermediates, which could underwent a variety of interesting transformations. Moreover, recent progress in metal carbene-based sulfur ylide approaches have also been introduced. Both the progress in asymmetric catalysis variants and reactions in aqueous solution have been presented. The second section describes the transformations using stabilized sulfonium salts and sulfur ylides as bench-stable reactants. The extra stability of these species is accompanied by a compromise in the reactivity, which usually requires developing activation methods. With transition metal catalysts to activate sulfonium salts, they have been discovered as efficient coupling partners in carbon-carbon bond and carbon-heteroatom bond formation reactions. Stable sulfur ylides could also be utilized to install fluorine-containing groups in a large variety of transformations. The third section covers recent progress in employing sulfonium salts as catalysts in organic reactions. The acidity of the α C−H in sulfonium salt is relatively high than its nitrogen and phosphine analogues. Therefore, it could be easily removed to form the sulfur ylide, which have restricted its application as catalysts. On one hand, scientists took advantage of these properties and developed new cyclic sulfonium salts as hydrogen bonding catalysts. On the other hand, sulfonium salts could be used as stable phase transfer catalysts under base free conditions in order to avoid degradations. Finally, the review discussed the limitations of the known chemistry in this field as well as the future opportunities. Sulfur ylide and sulfonium salts have displayed many unique reactivities as summarized in this review. New reactivity will still be the central theme of research given the importance of organosulfur compounds. In addition, insights into the factors controlling the reactivity via mechanistic studies will be of great importance for further research and development. Moreover, the applications of sulfonium salts as organocatalysts are still limited to a relatively narrow range of transformations. Therefore, it remains to be an elusive task to unlock their full potential, and future research must include the development of scalable and cost-efficient methods, broadening of reaction scopes, and integration with other catalytic manifolds. We hope that this review will pique the interests of readers and deliver inspiration for future development in this interesting and promising field.

The direct dearomatization reaction of isoquinolines and quinolines with chloroform has been accomplished through in situ electrophilic aryne activation and nucleophile formation. This transition metal-free protocol shows a broad scope of substrates, providing consistently high yields of medicinally-important dihydro(iso)quinoline derivatives. The utility of this method has been further demonstrated in the synthesis of deuterated analogues.

Herein, we report an aryne triggered ring-opening fluorination protocol of a great variety of saturated sulfur heterocycles. A key factor for the success is the identification of a suitable mediator. Compared to previous methods, this transition-metal free protocol employs low-cost potassium fluoride as the fluorine source. The operational simplicity and mild reaction conditions allow for the rapid synthesis of a wide range of aliphatic fluoride compounds in good yields.

Organosulfides are a common class of structure units in bioactive molecules and functional materials motivating continuous developments of efficient synthetic methods. Herein, we report an electrophilic aryne-activated ring opening protocol of one or two heteroatom containing saturated sulfur heterocycles. This three-component transformation proceeds under mild reaction conditions and displays exceptional generality of nucleophiles (C, O, S, N, and F centered nucleophiles), giving structurally diverse thioethers in good yields.

A facile and efficient synthesis of pyrroles from readily available amino acids is described. The key step in the method is an aza-Wacker oxidative cyclization catalyzed by palladium(II)/Cu(OTf)2. A series of pyrroles were obtained by this method under mild conditions.

A novel palladium-catalyzed addition of alcohols to olefins was developed, in which a migration of double bond was involved. By this new method, a variety of allylic ethers were prepared with moderate to high yields under mild conditions.