DABCO-promoted highly diastereo- and regioselective construction of C-3 functionalized spirooxindoles via [3 + 2] cycloaddition of 2-aryl/heteroarylidene-1H-indene-1,3(2H)-diones with N-2,2,2-trifluoroethylisatin ketimines at ambient conditions

The application of 2-aryl/heteroarylidene-1H-indene-1,3(2H)-dione as an activated olefin source in the DABCO-catalyzed [3 + 2] cycloaddition with N-2,2,2-trifluoroethylisatin ketimines has been disclosed. This highly efficient 1,3-dipolar cycloaddition reaction offered a variety of trifluoro methyl group bearing spiro-pyrrolidine linked oxindoles with four consecutive stereocentres in good to excellent yield and excellent diastereoselectivity. The synthetic practicality of the protocol was established by demonstrating the enantioselective construction of spiro-pyrrolidine-oxindoles with two vicinal spiro-quaternary chiral centres in good yield excellent enantioselectivity (>90% ee) by using ultralow loading of quinine as the catalyst at room temperature.

Indane-1,3-Dione: From Synthetic Strategies to Applications

Indane-1,3-dione is a versatile building block used in numerous applications ranging from biosensing, bioactivity, bioimaging to electronics or photopolymerization. In this review, an overview of the different chemical reactions enabling access to this scaffold but also to the most common derivatives of indane-1,3-dione are presented. Parallel to this, the different applications in which indane-1,3-dione-based structures have been used are also presented, evidencing the versatility of this structure.

Engaging Isatins in Multicomponent Reactions (MCRs) - Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained.

Transition metal-catalyzed synthesis of spirooxindoles

Spirooxindole is a principal bioactive agent and is observed in several natural products including alkaloids. They are broadly studied in the pharmaceutical field and have a significant role in the evolution of drugs such as anti-viral, anti-cancer, anti-microbial etc. In organic chemistry, an indispensable role is presented by transition metal catalysts. An effective synthetic perspective to spirooxindoles is the use of transition metals as the catalyst. This review discusses the synthesis of spirooxindoles catalyzed by transition metals and covers literature up to 2020.

A copper-catalyzed synthesis of aryloxy-tethered symmetrical 1,2,3-triazoles as potential antifungal agents targeting 14 α-demethylase

The search for potent therapeutic agents has prompted the design and synthesis of a library of twenty-six aryloxy-tethered and amide-linked symmetrical 1,2,3-triazoles (8a–z) using a copper(i)-catalyzed click chemistry approach.

Access to molecular complexity. Multicomponent reactions involving five or more components

The evaluation of the significance of a chemical transformation addresses many factors, including such important characteristics as the number of chemical bonds formed in one step, the reaction time, labour intensity, the cost of reactants and catalysts and so on. The amount of waste produced in the reaction has also gained increasing importance in recent years. Multicomponent reactions (MCRs) occupy a special place as a synthetic tool in modern organic chemistry. These reactions allow the synthesis of target products with complex structures, minimizing labour costs. This review summarizes the literature on multicomponent reactions involving five or more components. The data in the review are classified according to the number of reactants participating in the reaction and the types of reactions. It is worth noting that in some cases, these transformations can be a part of a domino process, making this classification difficult, if not impossible. The structural diversity of the reaction products greatly increases with increasing number of components involved in the MCR, which becomes virtually unlimited when using combinations of MCRs. This review highlights the main trends of past decades in the field of MCRs. The last two decades have witnessed an explosive growth in the number of publications in this area of chemistry.

The bibliography includes 309 references.

Microwave Assisted Surfactant-Thermal Synthesis of Metal-Organic Framework Materials

This research explores the application of surfactants as green solvents for the rapid microwave synthesis of metal-organic framework (MOF) materials. Lead, copper, and iron metal-organic framework materials were synthesized using surfactant-thermal microwave synthesis. The MOF materials were characterized by powder X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. With the exception of the iron MOF, which was expected to be amorphous, the MOF materials are crystalline, though generally exhibiting smaller crystals than those achieved with traditional solvothermal synthesis. This green synthetic method reduced synthesis time and reduced the use of traditional organic solvents as the reaction media.

Solubility of Some Mineral Salts in Polyethylene Glycol and Related Surfactants

The ambient solubility of the mineral salts NaCl, KCl, CsCl, KBr, K2SO4 and CuSO4 is reported as a function of composition of mixed binary solvents consisting of water with polyethylene glycol (PEG 200), ethoxylated C9–11 alcohols (C10E6) and ethoxylated, or propoxylated C10–12 alcohols (C11E6P1). Solubility gradually decreases with decreasing water content and follows the order PEG 200 > C10E6 > C11E6P1. Solubility of CsCl and KBr was found to be surprisingly high in neat PEG 200, on the order of 1 mol kg−1, and in neat C10E6, on the order of 0.1 mol · kg−1. The observed solubility trends are explained by the theory of hard and soft acids and bases under the consideration of the polarity of the surfactants.

Anatase TiO2 Mesocrystals: Green Synthesis, In Situ Conversion to Porous Single Crystals, and Self-Doping Ti3+ for Enhanced Visible Light Driven Photocatalytic Removal of NO

Mesocrystals are of great interest for a wide range of applications owing to their unique structural features and properties. The realization of well-defined metal oxide mesocrystals through a facile and green synthetic approach still remains a great challenge. Here, a novel synthesis strategy is reported for the production of spindle-shaped anatase TiO₂ mesocrystals with a single-crystal-like structure, which was simply achieved through the one-step hydrolysis reaction of TiCl₃ in the green and recyclable media polyethylene glycol (PEG-400) without any additives. Such anatase mesocrystals were constructed from small nanocrystal subunits (≈1.5-4.5 nm in diameter) and formed through oriented aggregation of the nanocrystals pre-formed in the reaction system. Owing to their novel structural characteristics, the as-synthesized anatase mesocrystals could be easily fused in situ into porous single crystals by annealing in air. More significantly, after being annealed in vacuum, Ti³⁺ sites could be easily induced in the anatase crystal lattice, resulting in the formation of Ti³⁺ self-doped anatase mesocrystals. The thus-transformed mesocrystals exhibited enhanced visible light activity towards the photocatalytic oxidation of nitric oxide (NO) to NO₃^- , which could be largely attributed to their intrinsic Ti³⁺ self-doped nature, as well as high crystallinity and high porosity of the mesocrystalline architecture.

A facile and green approach for the synthesis of spiro[naphthalene-2,5′-pyrimidine]-4-carbonitrile via a one-pot three-component condensation reaction using DBU as a catalyst

A series of novel spiro[naphthalene-2,5′-pyrimidine]-4-carbonitriles were synthesized using 1,3-dimethylbarbituric acid, aldehydes and cyclohexylidene malononitrile in presence of DBU. The structures were confirmed by spectral data and X-Ray crystallography.

One-pot four component domino strategy for the synthesis of novel spirooxindole pyrrolizine linked 1,2,3-triazoles via stereo- and regioselective [3 + 2] cycloaddition reaction in acidic medium

An efficient, one-pot four component condensation has been reported for the synthesis of spirooxindole pyrrolizine linked 1,2,3-triazolesvia[3 + 2] cycloaddition. The structures were confirmed by¹H NMR,¹³C NMR, mass spectra and X-ray.