Rh(III)-Catalyzed Oxidative C-2 Coupling of N-Pyridinylindoles with Benzo[b]thiophene 1,1-Dioxides via C-H Bond Activation

Tf2O/2-Chloropyridine-Triggered Synthesis of Benzo[b]thiophene 1,1-Dioxides from Sulfonium α-Acyl Sulfonylmethylides

Triflic anhydride and 2-chloropyridine-comediated tandem activation, intramolecular aromatic electrophilic addition, and 1,2-sulfonyl shift via spirocyclic intermediates of sulfonium α-acyl sulfonylmethylides realize the efficient synthesis of 2-alkyl/arylthiobenzo[b]thiophene 1,1-dioxides. The deactivated sulfonyl group determines the site-selectivity of the electrophilic addition via the ipso-attack, while the following S-migration controls the regioselectivity. Some of 2-methylthiobenzo[b]thiophene 1,1-dioxides show fluorescence properties in the solid state and in their solutions.

Palladium-Catalyzed C2-Selective Direct Arylation of Benzo[b]thiophene 1,1-Dioxides with Arylboronic Acids

A novel oxidative cross-coupling of benzo[b]thiophene 1,1-dioxides with arylboronic acids was reported. The efficient reaction occurred at the C2-position via C-H activation, followed by Pd(II)-catalyzed arylation. Furthermore, a series of C2-arylated products with significant photoluminescence properties have been synthesized and characterized, which illustrates the potential applications of our method in the aggregation-induced emission field.

Palladium-Catalyzed C2-Selective Oxidative Olefination of Benzo[b]thiophene 1,1-Dioxides with Styrenes and Acrylates

Here, we disclose a novel Pd(II)-catalyzed oxidative Heck reaction of benzo[b]thiophene 1,1-dioxides with styrenes and acrylates. This transformation features broad functional group tolerance and high C2 selectivity. Furthermore, the photoluminescence properties of C-2 alkenylated products have been characterized, which illustrates the potential usefulness of our protocol in constructing π-conjugated fluorescent molecules.

Cobalt(III)-catalyzed weakly coordinating arylurea-directed regioselective mono-olefination

Here, we developed an air-stable, earth-abundant cobalt(III)-catalyzed regioselective mono-olefination of arenes directed by urea under mild conditions through a cross-dehydrogenative coupling (CDC) process. Under the optimized conditions, a high regioselectivity of mono-olefination was achieved with various electron-rich and electron-deficient arenes, which afforded E-alkenylated products (with yields of up to 90%). In contrast to the conditions used for noble-metal-catalyzed olefination directed by weakly coordinating groups, our reaction was operated under mild conditions, including mild temperature (40 °C) and non-metallic oxidant.

Rhodium-Catalyzed Annulations and Heck Coupling/Aza-Michael Addition for the Synthesis of Benzothiadiazinoisoquinoline 6,6-Dioxides and Benzothiadiazinoisoindole 5,5-Dioxides, Respectively

A new and efficient protocol has been demonstrated for the synthesis of benzothiadiazinoisoquinoline 6,6-dioxides and benzothiadiazinoisoindole 5,5-dioxides in good to excellent yields. These compounds are formed through a sequential Rh(III)-catalyzed C-H cyclization of dihydrophenylbenzothiadiazine 1,1-dioxides with alkynes and oxidative Heck coupling/aza-Michael addition of dihydrophenylbenzothiadiazine 1,1-dioxides with acrylates, respectively.

Chemodivergent Synthesis of Indeno[1,2-b]indoles and Isoindolo[2,1-a]indoles via Mn(III)-Mediated or Electrochemical Intramolecular Radical Cross-Dehydrogenative Coupling

Chemodivergent synthesis of indeno[1,2-b]indoles and isoindolo[2,1-a]indoles from the same starting materials involving radical cross-dehydrogenative couplings have been developed. Mn(OAc)₃·2H₂O selectively promoted an intramolecular radical C-H/C-H dehydrogenative coupling reaction to provide indeno[1,2-b]indoles, while an intramolecular radical C-H/N-H dehydrogenative coupling reaction could proceed via electrochemistry to deliver isoindolo[2,1-a]indoles. Plausible mechanisms of the chemodivergent reactions were proposed.

Synthesis of Unsymmetrical Biheteroarenes via Dehydrogenative and Decarboxylative Coupling: a Decade Update

The design and development of robust and efficient methods for installing one heterocycle with another is endowed as a ubiquitous and powerful synthetic strategy to access complex organic biheterocycles in recent days due to their pervasive applications in medicinal as well as material chemistry. This perspective presents an overview on the recent findings and developments for the synthesis of unsymmetrical biheteroarenes via dehydrogenative and decarboxylative couplings with literature coverage mainly extending from 2011 to 2021. For simplification of the readers, the article has been subcategorized based on the catalysts used in the reactions.