Facile and Efficient One-Pot Synthesis of Anthraquinones from Benzene Derivatives Catalyzed by Silica Sulfuric Acid

Phthalic anhydride (PA): a valuable substrate in organic transformations

This review has been centralized on applications of phthalic anhydride (PA) as a valuable and significant heterocyclic substrate in two- and multicomponent organic reactions. The article has been subdivided into the following parts: (i) PA introduction by focusing on its characterization, synthesizing procedure, and multiple-aspect applications. In addition, the previous review articles based on PA have also been indicated; (ii) the applications of PA as a substrate have been subdivided into parts with a glance on the reaction components numbers; (iii) the applications of PA in esterification reactions; and (iv) some examples of PA in multistep synthesis. The review covers the corresponding literature up to the end of 2022. According to the abovementioned classifications, PA is a potent substrate to design a wide range of heterocyclic compounds that possess various kinds of properties and applications in chemistry, industry, and pharmaceuticals.

Tel-Cu-NPs Catalyst: Synthesis of Naphtho[2,3-g]phthalazine Derivatives as Potential Inhibiters of Tyrosinase Enzymes and Their Investigation in Kinetic, Molecular Docking, and Cytotoxicity Studies

Novel one-pot synthesis naphtho[2,3-g]phthalazine (1a–1k) of Mannich base derivatives can be achieved via grindstone chemistry using a Tel-Cu-NPs (telmisartan-copper nanoparticles) catalyst. This method offers efficient mild reaction conditions and high yields. Tyrosinase inhibitory activity was evaluated for all synthesized compounds, along with analysis of kinetic behavior and molecular docking studies. The synthesized compound, 1c was (IC50 = 11.5 µM) more active than kojic acid (IC50 = 78.0 µM). Lineweaver Burk plots were used to analyze the kinetic behavior of the most active compound 1c, it was reversible and competitive behavior. Compound 1c and kojic acid occurred in the presence of 2-hydroxyketone, which has the same inhibitory mechanism. The molecular docking of compound 1c and the control kojic acid were docked against 2Y9X protein via the Schrodinger Suite. The compound 1c showed a respectable dock score (−5.6 kcal/mol) compared to kojic acid with a dock score of (−5.2 kcal/mol) in the 2Y9X protein. Cytotoxicity activity was also evaluated by using HepG2 (liver), MCF-7 (breast), and HeLa (cervical) cancer cell lines, and high activity for 1c (GI50 = 0.01, 0.03, and 0.04 µM, respectively) against all cell lines was found compared to standard and other compounds. Therefore, this study succeeded in testing a few promising molecules as potential antityrosinase agents.

Mechanochemical Friedel-Crafts acylations

Friedel–Crafts (FC) acylation reactions were exploited in the preparation of ketone-functionalized aromatics. Environmentally more friendly, solvent-free mechanochemical reaction conditions of this industrially important reaction were developed. Reaction parameters such as FC catalyst, time, ratio of reagents and milling support were studied to establish the optimal reaction conditions. The scope of the reaction was explored by employment of different aromatic hydrocarbons in conjunction with anhydrides and acylation reagents. It was shown that certain FC-reactive aromatics could be effectively functionalized by FC acylations carried out under ball-milling conditions without the presence of a solvent. The reaction mechanism was studied by in situ Raman and ex situ IR spectroscopy.

Metal-Free Dehydrogenative Diels-Alder Reactions of Prenyl Derivatives with Dienophiles via a Thermal Reversible Process

An efficient dehydrogenative Diels-Alder reaction of prenyl derivatives with dienophiles has been developed. The reaction exhibits broad substrate scope and provides efficient access to cyclohexene derivatives with good to excellent yields. A reasonable mechanism involving a metal-free thermal reversible process is proposed.

Tandem buildup of complexity of aromatic molecules through multiple successive electrophile generation in one pot, controlled by varying the reaction temperature

While some sequential electrophilic aromatic substitution reactions, known as tandem/domino/cascade reactions, have been reported for the construction of aromatic single skeletons, one of the most interesting and challenging possibilities remains the one-pot build-up of a complex aromatic molecule from multiple starting components, i.e., ultimately multi-component electrophilic aromatic substitution reactions. In this work, we show how tuning of the leaving group ability of phenolate derivatives from carbamates and esters provides a way to successively generate multiple unmasked electrophiles in a controlled manner in one pot, simply by varying the temperature. Here, we demonstrate the autonomous formation of up to three bonds in one pot and formation of two bonds arising from a three-component electrophilic aromatic substitution reaction. This result provides a proof-of-concept of our strategy applicable for the self-directed construction of complex aromatic structures from multiple simple molecules, which can be a potential avenue to realize multi-component electrophilic aromatic substitution reactions.