Hydroxyl-Directed Ru(II)-Catalyzed Synthesis of Fused Dihydrofurans Using 1,4-Dioxane and Sulfoxonium Ylides as Annulating Agents

Copper-Mediated Decarboxylative Coupling of 3-Indoleacetic Acids with Sulfoxonium Ylides for the Synthesis of α-Acetoxyl Ketones

The most convenient and direct method of synthesizing an α-acyloxy ketone is the reaction of a diazo compound with a carboxylic acid via O-H insertion. However, due to the limitations in preparing and storing diazo compounds, the application of this method is restricted. In this study, Cu(OAc)2-mediated (OAc = acetate) decarboxylative coupling reactions of 3-indoleacetic acids with sulfoxonium ylides were developed for use in rapidly synthesizing α-acetoxyl ketones. In this reaction, Cu(OAc)2 was not only used as an oxidant, but also as acetate ion source. Notably, when 5-methoxy-2-methyl-3-indoleacetic acid reacted with different sulfoxonium ylides, the corresponding products exhibited fluorescence, and furthermore, several products displayed antiproliferative activities against various human cancer cell lines.

Microwave-Assisted Ru(II)-Catalyzed Regioselective Methyl Acylation of 2-Arylbenzoazoles: Synthesis of Benzofuran Conjugates via C-H Activation/Annulation

An efficient Ru(II)-catalyzed C-H functionalization protocol for 2-arylbenzoazoles as the directing group and sulfoxonium ylide has been developed. Gratifyingly, concomitant annulation was observed when 3-(benzo[d]azol-2-yl) phenol was used, enabling the construction of benzofuran conjugates. Notably, the utilization of water as the solvent and an energy efficient approach makes the reaction greener, contributing to overall sustainability. This protocol exhibits excellent scalability up to the gram scale with a diverse array of substitutions. Furthermore, the mechanism was examined by ESI-MS, and photophysical studies were also performed.

Development of novel transition metal-catalyzed synthetic approaches for the synthesis of a dihydrobenzofuran nucleus: a review

The synthesis of dihydrobenzofuran scaffolds bears pivotal significance in the field of medicinal chemistry and organic synthesis. These heterocyclic scaffolds hold immense prospects owing to their significant pharmaceutical applications as they are extensively employed as essential precursors for constructing complex organic frameworks. Their versatility and importance make them an interesting subject of study for researchers in the scientific community. While exploring their synthesis, researchers have unveiled various novel and efficient pathways for assembling the dihydrobenzofuran core. In the wake of extensive data being continuously reported each year, we have outlined the recent updates (post 2020) on novel methodological accomplishments employing the efficient catalytic role of several transition metals to forge dihydrobenzofuran functionalities.

Syntheses, reactivity, and biological applications of coumarins

This comprehensive review, covering 2021-2023, explores the multifaceted chemical and pharmacological potential of coumarins, emphasizing their significance as versatile natural derivatives in medicinal chemistry. The synthesis and functionalization of coumarins have advanced with innovative strategies. This enabled the incorporation of diverse functional fragments or the construction of supplementary cyclic architectures, thereby the biological and physico-chemical properties of the compounds obtained were enhanced. The unique chemical structure of coumarine facilitates binding to various targets through hydrophobic interactions pi-stacking, hydrogen bonding, and dipole-dipole interactions. Therefore, this important scaffold exhibits promising applications in uncountable fields of medicinal chemistry (e.g., neurodegenerative diseases, cancer, inflammation).

Synthesis of spiropyrans via Ru(II)-catalyzed coupling of 3-aryl-2H-benzo[b][1,4]oxazines with benzoquinones

An efficient Ru(II)-catalyzed C-H activation-based spiroannulation of benzoxazines with the easily available benzoquinone and N-sulfonyl quinone monoimine has been realized, providing a straightforward strategy to access NH-containing spiropyrans in moderate to good yields with good functional group compatibility. The procedure features atom- and step-economy, mild conditions, and excellent chemoselectivity. Moreover, a catalytically competent five-membered cycloruthenated complex has been isolated.

Synthesis of spiropyrans and arylquinones via Ru(II)-catalyzed condition-controlled coupling of 3-aryl-2H-benzoxazinones with benzoquinones

Ru(II)-catalyzed condition-controlled divergent coupling between 3-aryl-2H-benzoxazin-2-ones and benzoquinones has been realized under operationally simple conditions, affording a series of structurally stable spiropyrans and valuable arylquinones. The potential of this method is also demonstrated by scale-up synthesis and derivatization. Additionally, an unprecedented cycloruthenated complex has been identified as a key intermediate.

Ru(II)-catalyzed oxidative coupling of sulfoxonium ylides with amines: efficient synthesis of α-ketoamides and indolo[2,1-a]isoquinolines

The first use of sulfoxonium ylides for the synthesis of α-ketoamides is described via a Ru(II)-catalyzed amidation reaction with amines. The same Ru(II)-catalyzed reaction of sulfoxonium ylides with 2-phenylindoles provided indolo[2,1-a]isoquinolines instead of α-ketoamides.