A synthesis of 5-hetaryl-3-(2-hydroxybenzoyl)pyrroles

Metal-Free Catalyzed Oxidation/Decarboxylative [3+2] Cycloaddition Sequences of 3-Formylchromones to Access Pyrroles with Anti-Cancer Activity

An efficient and direct approach to pyrroles was successfully developed by employing 3-formylchromones as decarboxylative coupling partners, and facilitated by microwave irradiation. The protocol utilizes easily accessible feedstocks, a catalytic amount of DBU without any metals, resulting in high efficiency and regioselectivity. Notably, all synthesized products were evaluated against five different cancer cell lines and compound 3l selectively inhibited the proliferation of HCT116 cells with an IC50 value of 10.65 μM.

Bis(Benzofuran-1,3-N,N-heterocycle)s as Symmetric and Synthetic Drug Leads against Yellow Fever Virus

The yellow fever virus (YFV) is an emerging RNA virus and has caused large outbreaks in Africa and Central and South America. The virus is often transmitted through infected mosquitoes and spreads from area to area because of international travel. Being an acute viral hemorrhagic disease, yellow fever can be prevented by an effective, safe, and reliable vaccine, but not be eliminated. Currently, there is no antiviral drug available for its cure. Thus, two series of novel bis(benzofuran−1,3-imidazolidin-4-one)s and bis(benzofuran−1,3-benzimidazole)s were designed and synthesized for the development of anti-YFV lead candidates. Among 23 new bis-conjugated compounds, 4 of them inhibited YFV strain 17D (Stamaril) on Huh-7 cells in the cytopathic effect reduction assays. These conjugates exhibited the most compelling efficacy and selectivity with an EC50 of <3.54 μM and SI of >15.3. The results are valuable for the development of novel antiviral drug leads against emerging diseases.

Synthesis of 5H-Chromeno[2,3-d]pyrimidin-5-one Derivatives via Microwave-Promoted Multicomponent Reaction

A microwave-promoted multicomponent reaction of 3-formylchromones, amines, and paraformaldehyde was achieved under catalyst-free and solvent-free conditions, delivering 5H-chromeno[2,3-d]pyrimidin-5-one derivatives in good to excellent yields via an unexpected annulation pathway, which further expanded the synthetic application of paraformaldehyde as a C1 building block.

Synthesis of heterocyclic analogs of isoflavone and homoisoflavone based on 3-formylchromone

The review is focused on recent developments of chemistry of synthetic analogs of natural compounds, isoflavone and homoisoflavone. The possible synthetic strategies to access heterocyclic analogs of these compounds starting from readily available 3-formylchromone and its derivatives (3-cyanochromone, 2-amino-3-formylchromone) and products of its condensation with simplest C- and N-nucleophiles are discussed. The structural features of the reaction products that depend on the nature of the reaction medium, structure of the starting compounds, and reagent ratio are considered. Particular attention is given to the application of the modern strategies of organic synthesis, namely green chemistry approaches, click reactions, domino reactions, etc. Examples of compounds of this group most promising for clinical application due to wide and pronounced pharmacological effects are given.

Natural Hydroxyapatite: Green Catalyst for the Synthesis of Pyrroles, Inhibitors of Corrosion

Polysubstituted pyrroles have been synthesized in good yields via a four-component one-pot reaction of 1,3-dicarbonyl compounds, amines, aldehydes, and nitroalkanes using natural hydroxyapatite (HAp) as an efficient green catalyst. This strategy provides advantages such as simple experimental and work-up procedures, mild conditions, high selectivity, low cost, high atom economy, and environmental friendliness; it uses a green commercial catalyst and does not require a solvent. The electrochemical behavior of S300 steel in 1 M hydrochloric acidic was studied in the presence of these heterocyclic compounds. The results showed good inhibition efficiency for steel in acidic media.

A simple and convenient synthesis of 3-salicyloylquinoline-4-carboxylic esters from chromone and isatin

A simple and convenient synthesis of 3-salicyloylquinoline-4-carboxylic esters has been developed through an AlCl3-catalyzed reaction of easily available Baylis-Hillman adducts from chromones and isatin-derivatives. This reaction involves esterification, cyclization and ring opening in a one-step process, and provides an efficient approach for easy access to a series of valuable salicyloylquinoline derivatives with high yields. Moreover, this protocol offers several advantages, such as availability of starting materials, economic availability, operational simplicity and mild reaction conditions.

Iridium- and Rhodium-Catalyzed Directed C-H Heteroarylation of Benzaldehydes with Benziodoxolone Hypervalent Iodine Reagents

The C-H heteroarylation of benzaldehydes with indoles and pyrroles was realized using the benziodoxolone hypervalent iodine reagents indole- and pyrroleBX. Functionalization of the aldehyde C-H bond using either an o-hydroxy or amino directing group and catalyzed by an iridium or a rhodium complex allowed the synthesis of salicyloylindoles and (2-sulfonamino)benzoylindoles, respectively, with good to excellent yields (74-98%). This new transformation could be carried out under mild conditions (rt to 40 °C) and tolerated a broad range of functionalities, such as ethers, halogens, carbonyls, or nitro groups.

An analysis of the complementary stereoselective alkylations of imidazolidinone derivatives toward α-quaternary proline-based amino amides

Alkylations of proline-based imidazolidinones are described based on the principle of self-regeneration of stereocenters (SRS), affording high levels of either the cis or trans configured products. Stereoselectivity is dictated solely on the nature of the "temporary" group, where isobutyraldehyde-derived imidazolidinones provide the cis configured products and 1-naphthaldehyde-derived imidazolidinones afford the complementary trans configured products. These stereodivergent products can be readily cleaved to afford both α-alkylated proline enantiomers from readily available L-proline. A series of imidazolidinones were alkylated to investigate the origin of the anti-selectivity. Potential contributions toward the observed anti-selectivity are discussed on the basis of these experiments, suggesting a refined hypothesis for selectivity may be in order.

Synthesis of substituted pyrroles using a silver-catalysed reaction between isocyanoacetates/benzyl isocyanides and chromones

A novel synthetic strategy to construct substituted-pyrroles has been developed through silver-catalysed cycloadditions of isocyanides with chromones.