Palladium-Catalyzed Double Carbonylation Reactions of o-Dihaloarenes with Amines in Phosphonium Salt Ionic Liquids

Phthalimides: developments in synthesis and functionalization

Phthalimides, an important class of biologically active N-heterocycles, are not only found in pharmaceuticals, natural products, agrochemicals, polymers, and dyes, but also serve as building blocks in organic transformations. Many synthetic methods, including metal catalysis and metal-free systems, have been developed to prepare functionalized phthalimides. In this review, we describe the developments in the synthesis and functionalization of phthalimides over the past two decades.

N-heterocyclic carbene-catalyzed atroposelective synthesis of N-Aryl phthalimides and maleimides via activation of carboxylic acids

Traditionally, N-aryl phthalimides are synthesized by the condensation of phthalic anhydride and aniline derivatives, usually proceeding under harsh conditions. The alternative mild and organocatalytic strategies for their synthesis are underdeveloped. Herein, we demonstrate the organocatalytic atroposelective synthesis of N-aryl phthalimides via the traditional N-CC=O disconnection under mild conditions. The in-situ acid activation of phthalamic acid and subsequent N-heterocyclic carbene (NHC)-catalyzed atroposelective amidation allowed the synthesis of well-decorated N-aryl phthalimides in excellent yields and enantioselectivities. Mechanistic studies reveal the addition of NHC to the in situ generated isoimides, thus introducing a unique mode of generating acylazoliums. Interestingly, both enantiomers of the product can be accessed from the same phthalic anhydride and aniline using the same NHC pre-catalyst. Moreover, this strategy has been extended to the atroposelective synthesis of N-aryl maleimides.

Direct synthesis of phthalimides via palladium-catalysed double carbonylation of o-dihaloarenes with nitroarenes

The direct carbonylation of readily available nitro compounds is more attractive and straightforward than the use of traditional amines as nucleophiles. Herein, a practical palladium-catalysed double carbonylation of nitroarenes with o-dihaloarenes has been developed for the construction of various N-aryl phthalimides. Key to the success of this transformation is the use of Mo(CO)6, which acts as both a reducing agent and a solid carbonyl source. A wide range of nitroarenes and o-dihaloarenes as well as o-iodobenzoic acids reacted smoothly to give phthalimides in 27-94% yields.

Toxicity of ionic liquids in marine and freshwater microorganisms and invertebrates: state of the art

The variety of applications and expected growth in ionic liquid production are raising concerns about the release of these compounds into aquatic systems. Up to date, 103 studies have provided ecotoxicological data regarding the exposure effects of Ionic Liquids towards aquatic microorganisms and invertebrate species: 61 were devoted to freshwater species (n = 28), while marine species (n = 12) were mentioned in 42. The aim of this review, by gathering published studies on ionic liquids and model aquatic organisms, was to present the toxic effects described in distinct species and to understand which are the main factors influencing the toxicity of some ionic liquids. In accordance with the most recognized pattern, freshwater species were featured in a higher number of publications than marine ones. After literature analysis, algal species were the most represented organisms in aquatic toxicity assessments. Among tested compounds, the imidazolium cations in combination with long alkyl-chain anions, showed to be the most toxic one. In analytical terms, it is not straightforward to find the undissociated compound in a natural compartment, as ionic liquids are composed of ionic components, easily subjected to dissociation. Given the aforementioned, the present review paper points out the need of increasing the number of organisms being assessed in ionic liquids toxicity assays, in order to start defining monitoring procedures. Moreover, such would allow a better understanding of ionic liquids contamination status and, also, the opportunity to remark the effectiveness of new in silico methods for the ecotoxicity assessment of this kind of substances.

Palladium-Catalyzed Perfluoroalkylative Carbonylation of 2-Allylaryl Trifluoromethanesulfonates: Base-Controlled Selective Access to β-Perfluoroalkyl Amides

A palladium-catalyzed perfluoroalkylative carbonylation of 2-allylaryl trifluoromethanesulfonates has been developed. A range of 2-allyl trifluoromethanesulfonates, perfluoroalkyl halides, and amines were applied in this tandem procedure to provide the corresponding β-perfluoroalkyl amides with good functional group tolerance and high chemoselectivity. The final products were controlled by the base applied.

Influence of the alkyl chain length on the physicochemical properties and microbial biocompatibility of phosphonium based fatty acid ionic liquids

Ionic liquids (ILs) have remarkable properties and applications in many areas of science. Phosphonium ILs have become important because of their unique chemical and thermal stabilities. The present work is focused on the synthesis, characterisation, physicochemical properties, and microbial toxicity assessment of phosphonium ILs bearing seven different fatty acid anions. The structures of the synthesised ILs were confirmed by 1H and 13C nuclear magnetic resonance (NMR) and FTIR spectroscopy. Physicochemical properties such as density and viscosity of pure ILs were measured at temperatures ranging from 298.15 to 313.15 K. The experimental density decreased, whereas the viscosity increased with an increasing number of carbon atoms in the anion. The derived properties were also found to be anion dependent. The thermal decomposition temperature was investigated by TGA. Subsequently, the toxicity profile of the ILs was determined for selected Gram positive and Gram negative bacteria and some species of fungi in terms of minimum inhibitory concentrations (MIC). The results show that the antimicrobial activities of the ILs are strongly related to the structures of the ILs, where an increase in toxicity was observed with increasing alkyl group chain length of the fatty acid anion.

Tuning the LUMO Levels of Z-Shaped Perylene Diimide via Stepwise Cyanation

The central dogma in constructing organic electron acceptors is to attach electron-withdrawing groups to polycyclic aromatic hydrocarbons. Yet, the full potentials of many organic acceptors were never realized due to synthetic obstacles. By combining the Wittig-Knoevenagel benzannulation, the Pd(0)-catalyzed cyanation, and nucleophilic addition/oxidation cyanation, six polynitrile Z-shaped perylene diimide were synthesized. These stable and soluble electron acceptors possess LUMO energy levels comparable with those of benchmark compounds. Electrochemical investigation reveals that each additional nitrile group reduces the LUMO energy by 0.2 eV.

Photochemical intermolecular dearomative cycloaddition of bicyclic azaarenes with alkenes

Dearomative cycloaddition reactions represent an ideal means of converting flat arenes into three-dimensional architectures of increasing interest in medicinal chemistry. Quinolines, isoquinolines, and quinazolines, despite containing latent diene and alkene subunits, are scarcely applied in cycloaddition reactions because of the inherent low reactivity of aromatic systems and selectivity challenges. Here, we disclose an energy transfer-mediated, highly regio- and diastereoselective intermolecular [4 + 2] dearomative cycloaddition reaction of these bicyclic azaarenes with a plethora of electronically diverse alkenes. This approach bypasses the general reactivity and selectivity issues, thereby providing various bridged polycycles that previously have been inaccessible or required elaborate synthetic efforts. Computational studies with density functional theory elucidate the mechanism and origins of the observed regio- and diastereoselectivities.

"On water" nano-Cu2O-catalyzed CO-free one-pot multicomponent cascade cyanation-annulation-aminolysis reaction toward phthalimides

An efficient nano-Cu2O-catalyzed cascade multicomponent reaction of 2-halobenzoic acids and trimethylsilyl cyanide with diverse amines was developed using water as a solvent, affording versatile N-substituted phthalimide derivatives in moderate to excellent yields. This novel strategy features carbon monoxide gas-free, environmentally benign, one-pot multistep transformation, commercially available reagents, a cheap catalyst without any additives, wide functional group tolerance, and operational convenience.

Beyond conventional construction of the phthalimide core: a review

This review highlights (2010–2021) different strategies for the construction of the phthalimide core apart from traditional synthetic routes.

One-Pot Domino Carbonylation Protocol for Aromatic Diimides toward n-Type Organic Semiconductors

Aromatic diimides are one of the most important chromophores in the construction of n-type organic semiconductors, which lag far behind their p-type counterpart but are necessary for ambipolar transistors, p-n junctions and organic complementary circuits. Herein, we establish a facile one-pot domino synthetic protocol for aromatic diimides via palladium-catalyzed carbonylation of tetrabromo aromatic precursors. Taking tetrabromocorannulene (TBrCor) and tetrabromo-2,7-di-tert-butylpyrene (TBrPy) as the typical examples, we obtained diimide derivatives in yields of about 50 %, one order of magnitude higher than that of the traditional multi-step diimidization. As demonstrated in the case of corannulene diimide, the efficient diimidization not only allows the LUMO levels to be lowered significantly but also provides an ordered and closer packing structures, opening up possibilities to the development of n-type semiconducting materials based on a variety of aromatic systems.

An emerging integration between ionic liquids and nanotechnology: general uses and future prospects in drug delivery

There is a growing need to develop drug-delivery systems that overcome drawbacks such as poor drug solubility/loading/release, systemic side effects and limited stability. Ionic liquids (ILs) offer many advantages and their tailoring represents a valuable tuning tool. Nano-based systems are also prized materials that prevent drug degradation, enhance their transport/distribution and extend their release. Consequently, structures containing ILs and nanoparticles (NPs) have been developed to attain synergistic effects. This overview on the properties of ILs, NPs and of their combined structures, reveals the recent advances in these areas through a review of pertinent literature. The IL-NP structures present enhanced properties and the subsequent performance upgrade proves to be useful in drug delivery, although much is yet to be done.

Selective formation of phthalimides from amines, aldehydes and CO by Pd-catalyzed oxidative C–H aminocarbonylation

The Pd/Cu-catalyzed intramolecular C–H bond aminocarbonylation utilizing imines as the amine source has been developed. This transformation provides an efficient and straightforward protocol for the synthesis of phthalimides which widely exist in natural products, pharmaceutical and functional materials. Various functional groups are tolerated and the yields are up to 99%.

Palladium-Catalyzed Highly Chemoselective Intramolecular C-H Aminocarbonylation of Phenethylamines to Six-Membered Benzolactams

A palladium-catalyzed highly selective intramolecular C-H aminocarbonylation of Br-functionalized phenethylamines in the presence of CO was achieved while leaving the C-Br bond unreacted to afford six-membered benzolactams with good to high yields. The remaining C-Br group in the cyclized product was successfully used as a reactive center for further functionalization through various palladium-catalyzed coupling reactions.

Reactant cum solvent water: generation of transient λ3-hypervalent iodine, its reactivity, mechanism and broad application

We have demonstrated a benign strategy for amides, imides and their chiral analogues using water as a source of carbonyl oxygen and medium. DFT-MIR studies and controlled experiments established the mechanism involving PhI(OH)₂-bearing intermediates.

MnO2 catalyzed formylation of amines and transamidation of amides under solvent-free conditions

A facile and efficient MnO₂ catalyzed one-pot protocol for formylation of amine and transamidation of primary and secondary amides by amines has been developed.

Palladium nanoparticles in glycerol: a clear-cut catalyst for one-pot multi-step processes applied in the synthesis of heterocyclic compounds

Palladium/TPPTS nanoparticles in glycerol represent a versatile catalyst leading to a large variety of heterocycles through domino/sequential one-pot approaches.

Versatile and sustainable synthesis of cyclic imides from dicarboxylic acids and amines by Nb2O5 as a base-tolerant heterogeneous Lewis acid catalyst

Catalytic condensation of dicarboxylics acid and amines without excess amount of activating reagents is the most atom-efficient but unprecedented synthetic method of cyclic imides. Here we present the first general catalytic method, proceeding selectively and efficiently in the presence of a commercial Nb2 O5 as a reusable and base-tolerant heterogeneous Lewis acid catalyst. The method is effective for the direct synthesis of pharmaceutically or industrially important cyclic imides, such as phensuximide, N-hydroxyphthalimide (NHPI), and unsubstituted cyclic imides from dicarboxylic acid or anhydrides with amines, hydroxylamine, or ammonia.

Efficient and scalable Pd-catalyzed double aminocarbonylations under atmospheric pressure at low catalyst loadings

A scalable approach to access various pharmaceutical and structurally intriguing N-substituted phthalimides via double aminocarbonylations has been established under atmospheric CO pressure with a robust Pd-NHC complex at a low catalyst loading.

Polymer supported Pd catalyzed carbonylation of aryl bromides for the synthesis of aryl esters and amides

A new polymer anchored Pd(ii) Schiff base catalyst has been synthesized for the evaluation of alkoxycarbonylation and aminocarbonylation reactions of various substituted aryl bromides with alcohols and amines.

Efficient palladium-catalyzed double carbonylation of o-dibromobenzenes: synthesis of thalidomide

A convenient and mild procedure for double carbonylation of o-dibromobenzene with various 2-amino pyridines and naturally occurring amines has been developed. N-Substituted phthalimides were produced in good to excellent yields. Furthermore, thalidomide was produced in excellent yield under these conditions.