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Barbituric acids mono-substituted at the 5-position show keto–enol tautomerism. In the keto form, conjugation to an aryl substituent is interrupted due to the sp³-hybridized carbon atom at the 5-position of barbituric acid. The enol form generates a conjugated π-system to the aryl substituent and acts as an electron-donating group. If the aryl substituent is electron-deficient, a push-pull system is generated that shows typical UV/Vis absorption. These types of compounds are difficult to access synthetically due to their intrinsic convertibility. The synthesis of barbituric acids with a 4-formylphenyl functionality at the 5-position is reported. This compound, 5-(4-formylphenyl)barbituric acid, could be used to introduce extended π-systems with electron-withdrawing groups in great variety by simple condensation reactions. We demonstrate this by a Horner–Wadsworth–Emmons reaction that forms the enolizable dye (E)-5-(4-(4-nitrostyryl)phenyl)barbituric acid.

Cancer is one of the most daunting illnesses in the world as compared to many other human diseases. This review article aims to summarize the literature that is already published based on heterocyclic anticancer compounds. Under this broad topic we try to shed a light on anticancer potentiality of oxygen-, sulfur-, and nitrogen-containing heterocyclic compounds, such as quinolines, pyrroles, pyrimidines, pyridines, indoles, also sulfonamides linked heterocycles, benzimidazoles and oxadiazoles.

1 Introduction

1.1 Drugs in Use for Cancer Treatment

1.2 Recently Discovered Anticancer Drugs

2 Various Classes of Compounds as Anticancer Agents

2.1 Quinoline Derivatives as Anticancer Agents

2.2 Benzimidazoles as Anticancer Agents

2.3 Indole: A Privileged Scaffold for the Design of Anticancer Agents

2.4 Pyrimidine Derivatives as Anticancer Agents

2.5 Pyridine Derivatives as Anticancer Agents

2.6 Pyrrole Derivatives as Anticancer Agents

2.7 Sulfonamides linked with heterocycles as Anticancer Agents

2.8 Oxadiazole and Its Derivatives as Anticancer Compounds

2.9 Benzothiazole-Triazole Hybrids as Anticancer Compounds

3 Conclusion

In recent years, macrocycles have emerged as efficient and sustainable photosensitizers for the catalysis of organic transformations. This graphical review provides a concise overview of photocatalysis and photoredox catalysis utilizing three common macrocycles: porphyrins, phthalocyanines and corroles. They exhibit strong absorption in the visible region and can be easily oxidized or reduced, making them good candidates for photocatalysis.

In recent years, there has been a notable surge in the utilization of microwave energy, leading to the emergence of innovative and groundbreaking methods across various branches of chemistry, including organic synthesis, materials science, heterocyclic chemistry, and medicinal chemistry. This comprehensive literature review delves into the microwave-assisted organic synthesis of specific heterocycles, illuminating its effectiveness in producing diverse molecules with heightened efficiency and selectivity. The review highlights the significant role of microwave irradiation as a potent method for constructing a wide range of compounds. Particular emphasis is placed on the impact of the technique on synthesizing various hybrids such as 1,2,3-triazole hybrids, coumarin hybrids, imidazopyridine hybrids, phenanthridines hybrids, carbene hybrids, and oxazole hybrids. This article is valuable as it offers insights into current synthetic procedures and trends in developing innovative medications utilizing heterocyclic compounds.

1 Introduction

2 Synthesis of 1,2,3-Triazole Hybrids

3 Coumarin Hybrids

4 Imidazo Pyridine Hybrids

5 Phenanthridine Hybrids

6 Carbene Hybrids

7 Oxazole Hybrids

8 Conclusion

We report a straightforward formylation at position 7 of pyrazolo[1,5-a]pyrazine derivatives featuring substituents at the 2,3,4 positions. N,N,N′,1,1,1-Hexamethylsilanecarboximidamide exists in equilibrium with its carbene form due to 1,2-migration of the silyl group. The ensuing carbene can be inserted into the most acidic C–H group of the pyrazolo[1,5-a]pyrazines. The most acidic calculated pK_a (DMSO) C–H group is at position 7 and does not depend significantly on the substituents. The reactions proceed in high yields affording aminals that can be hydrolyzed to the corresponding aldehydes. Methanolysis of the aminals affords the corresponding methylimines. The constitution of the aminals was unambiguously proved by X-ray crystal structure analysis of a set of derivatives. The method is simple, often does not require even solvents, and can be extended to other heterocyclic compounds.

The cross-dehydrogenative coupling between isochromans and nucleophiles using an electronically tuned nitroxyl radical catalyst, which effectively promotes the oxidation of benzylic ethers, has been investigated. Using sulfonamides as a nucleophile, modification of isochromans via oxidative C–N bond formation has been achieved at ambient temperature.

The electrochemical fixation of carbon dioxide onto organic matter has emerged as a promising approach in recent years. By combining the unique features of electrochemistry with the goal of carbon dioxide fixation, researchers aim to develop new strategies that can contribute to a more sustainable and environmentally friendly synthesis of organic compounds. One advantage of electrochemical methods is their ability to provide both electrons and energy for chemical transformations. This allows for the direct conversion of carbon dioxide into valuable organic products, without the need for transition metal catalysts or harsh reaction conditions. As a result, electrochemical carbon dioxide fixation offers the potential for milder and more efficient processes compared to traditional methods. Scientists have made noteworthy progress in exploring different strategies for the fixation of carbon dioxide under electrochemical conditions. These strategies involve the activation of various types of chemical bonds, including C(sp²)–C(sp²), C(sp²)–H, C–X (X = halogen), and C(sp³)–X (X = S, C, O, N). This review aims to provide an overview of the current state of research on electrochemical carbon dioxide fixation into organic matter. It will discuss the different strategies employed, the key findings, and the challenges that remain to be addressed. By highlighting the recent advancements in this field, this review hopes to inspire further exploration and innovation in the area of electrochemical synthesis for carbon dioxide fixation.

1 Introduction

2 Electrocatalytic Monocarboxylation of CO₂

2.1 Monocarboxylation of C(sp²)–C(sp²)

2.2 Monocarboxylation of C(sp²)–H

2.3 Monocarboxylation of C–X (X = Cl, Br, I)

2.4 Monocarboxylation of C(sp³)–X (X = S, C, O, N)

3 Electrocatalytic Dicarboxylation of CO₂

4 Electrocatalytic Esterification of CO₂

5 Conclusions

Butadienyl ketene is a useful intermediate because of its role as a 2p-component in cycloaddition reactions with a variety of substrates such as simple or conjugated imines and dienes. This review article summarizes recent reports on the generation of butadienyl ketene in situ and their cycloaddition reactions to afford heterocyclic systems. The chemistry of butadienyl ketene is explored with a focus on its [2+2] and [4+2] cycloaddition reactions with a variety of imines and azadiene derivatives such as 1,3-diazabuta-1,3-dienes, for the synthesis of four- and six-membered heterocycles, respectively.

SIRT1 enzyme is a key family member of Silent Information Regulators (Sirtuins), which catalyze the deacetylation of proteins. Therefore, developing new SIRT1 inhibitors has potential application in treating cancer disease and age-related metabolic disorders. In this study, we synthesized a series of N-acylhydrazone (NAH) derivatives and performed high-throughput screening of their inhibitory activity against the recombinant SIRT1 protein by a luminescent assay. Using in silico screening, we identified a new NAH derivative that features both selectivity and a high binding affinity towards the active pocket of SIRT1 that are comparable to known inhibitors such as Ex527 and Sirtinol. Such high binding affinity makes the new derivatives promising alternatives to the available inhibitors and holds promise for developing better-targeted drugs against SIRT1 activity.

We disclose a useful approach to novel tetrahedral building blocks containing N-heterocycles. Pyrrole was introduced on to the tetraphenylmethane (TPM) core by employing the RCM strategy, Clauson–Kaas reaction, Paal–Knorr condensation, and Ullmann coupling as key steps. In addition, various heterocyclic derivatives of TPM were prepared using nickel catalysts. We also studied the photophysical properties of the synthesized TPM derivatives containing different peripheral substituents and found that they exhibit high quantum yields.