Recent Developments in the Synthesis of Bicyclic Condensed Pyrimidinones

Functionalized bicyclic pyrimidinones and their derivatives are significant heterocyclic scaffolds being their all-around prevalence in biologically potent compounds. In several attempts to explore the different synthetic methodologies for the construction of bicyclic condensed pyrimidinones, different researchers from all across the globe have reported numerous substantial methods. In the present review, considerable work has been critically compiled on the synthesis of substituted and functionalized bicyclic pyrimidinones from 2000 onwards.

Application of Multi-component Reaction in the Synthesis of Heterocyclic [3.3.3] Propellane Derivatives

Propellanes and derivatives have attractive properties due to their unique structure. Therefore, [3.3.3] propellanes, containing tricyclic structures with one of the carbon-carbon bonds common in three rings, were used in natural products, pharmaceutical compounds, and heterocyclic compounds, which were biologically important. The various multi-component reactions were applied in the synthesis of propellanes, which were highlighted throughout this review

Recent Advances in the Application of Barbituric Acid Derivatives in Multicomponent Reactions

Barbituric acid is a pyrimidine heterocyclic organic compound, which is pharmacologically active. It is important to build structures containing various medicinal activities. This compound attracts the scientific research community in organic synthesis. It can be used in the synthesis of polyheterocyclic, natural, medicinal compounds, and organic sensors. Herein, the utilization of barbituric or thiobarbituric acid in multicomponent reactions is reported from 2016-2021 in this manuscript.

Recent advances in the synthesis of benzothiazole and its derivatives

Benzothiazoles have recognized pharmacophores in the field of research, predominantly in synthetic and medicinal chemistry, on account of their significant pharmaceutical properties. This important class of derivatives endows an extensive range of biological activities like anti-inflammatory, antidiabetic, anticancer, anticonvulsant, antibacterial, antiviral, antioxidant, antituberculosis, enzyme inhibitors, etc. Hence, various methodologies have been accomplished to synthesize benzothiazole compounds considering the purity, yield, and selectivity of the products. This review provides different reaction methods that are involved in the synthesis of a variety of benzothiazole derivatives.

Carboxylation of alkenes and alkynes using CO2 as a reagent: an overview

: CO2 fixation reactions are of paramount interest both from economical and environmental perspectives. As an abundant, non-toxic, and renewable C1 feedstock, CO2 can be utilized for the synthesis of fuels and commodity chemicals under elevated reaction conditions. The major challenge in the CO2 utilization reactions is its chemical inertness due to high thermodynamic stability and kinetic barrier. The carboxylation of unsaturated hydrocarbons with CO2 is an important transformation as it forms high-value reaction products having industrial as well as medicinal importance. This mini-review is mainly focused on the recent developments in the homogeneously and heterogeneously catalyzed carboxylation of alkenes and alkynes by using carbon dioxide as a reagent. We have highlighted various types of carboxylation reactions of alkenes and alkynes involving different catalytic systems, which comprise mainly C-H bond activation, hydrocarboxylation, carbocarboxylation, heterocarboxylation, and ring-closing carboxylation, including visible-light assisted synthesis processes. The mechanistic pathways of these carboxylation reactions have been described. Moreover, challenges and future perspectives of these carboxylation reactions are discussed.

Synthesis of Open-Resorcinarene Dendrimers with L-serine(ibuprofen) Derivatives

: A new class of dendrimers with open-resorcinarenes has been synthesized in good yields (77-85%). The open-resorcinarenes showed a high capacity for functionalization, having eight hydroxyl groups. The Williamson reaction with N,N-bis(2-azidoethyl)-2-bromo acetamide did not show any steric effect, obtaining sixteen azide terminal groups, which gave us the possibility to obtain a high molecular weight dendrimer via the azide-alkyne click reaction with prop-2-yn-1-yl-(ibuprofen)L-serinate derivatives to obtain the triazole ring spacers and the L-serinate(ibuprofen) derivatives as terminal groups. Also, we carried out the deprotection reaction of the L-serinate moiety terminal groups of the dendrimer 10 in good yields (95%). Three novel open-resorcinarene den-drimers with sixteen ibuprofen-L-serinate derivatives and hydroxyl, tert-butyl, and carboxylic acid; therefore, with three different terminal groups, with possible nanomedical activity are reported.

Quantitative Estimate of the Resonance Effects in some Unsaturated, Monocyclic, and Aromatic Hydrocarbons Based on the Renewed Optical Exaltations

: The present review discusses a new viewpoint on refractometry as the oldest experimental physical method, whose scientific potential in the estimation of structural effects in organic chemistry has been missed so far. The author demonstrates that upon certain adjustment and redesign of refractometry, this potential can be tapped and successfully used to determine a type of Π-electron interaction, delocalization degree of Π-electrons in organic compounds, and to perform quantitative estimates of resonance effects in unsaturated, (polycyclic) aromatic, and other polyconjugated systems (e.g., fullerenes). The method for accurate separation of molar refraction into additive and constitutive components was suggested; the method is based on the specially developed additive scheme. It was revealed that the negative deviations from additivity for cycloalkanes depend linearly on the number of carbon atoms in the ring. Excellent linear correlations between renewed optical exaltations, the number of Π-electrons in a conjugated system, and experimentally found resonance energy (determined from hydrogenation heat values) were demonstrated. Angular coefficients of the correlation series (ρ-constants) are considered as a criterion of classification, which characterizes the degree of mobility of Π-electrons in the conjugated system of a given type. It is emphasized that the development of methods for precise measurement of the constitutive components of molar refraction may become a useful additional source of information about resonance and other effects in organic and polymer chemistry.

Hydroxyethyl Isoflavonoids from the Leaves of Maclura tricuspidata

: Maclura tricuspidata, which belongs to the Moraceae family, is widely distributed in Asia, including Korea. All parts of this plant, such as roots, fruits, and leaves, are rich in diverse bioactive compounds, especially xanthones and isoflavonoids. Investigation of the leaves of M. tricuspidata through various chromatographic techniques yielded fourteen compounds, including five new compounds. The new compounds were determined to comprise an isoflavonoid structure with hydroxyethyl moiety and defined as hydroxyethylisoflavones A-E (10-14) on the basis of 1D and 2D NMR and MS data. These compounds efficiently inhibited α-glucosidase activity.