Base-promoted synthesis of dihydrochromeno[4,3-d]pyrrolo[3,4-b]pyridines from 4-chloro-3-substituted coumarins and α-aminomaleimides.

This paper describes the base-mediated cascade reactions of 4-chloro-3-substituted coumarins with α-aminomaleimides, allowing the efficient synthesis of dihydrochromeno[4,3-d]pyrrolo[3,4-b]pyridines with interesting chemoselectivity. These transformations include the domino-style formation of C-C/C-N bonds through a base-mediated nucleophilic substitution, Michael addition, N-cyclization, and elimination. The presented synthetic strategy has several advantages: it is simple, uses readily available starting materials and an environmentally friendly solvent, has a highly chemoselective route, and allows the purification of products via washing with EtOH (96%), a technique called GAP (Group-Assisted-Purification) chemistry.

Base-Promoted Reaction of 4-Chloro-3-vinyl Coumarins, Phenacylpyridinium Bromides, and Elemental Sulfur: A Designed Approach to Thiopyrano[4,3-c]chromen-5(1H)-ones.

A designed synthesis of thiopyrano[4,3-c]chromen-5(1H)-ones was developed based on a base-promoted three-component reaction between 4-chloro-3-vinyl coumarins, phenacylpyridinium bromides, and elemental sulfur. Readily available starting materials, mild conditions, chemoselectivity, operational simplicity, and synthetically useful yields are some highlighted advantages of these transformations.

A review of the synthetic strategies toward spirobarbiturate-fused 3- to 7-membered rings.

Spiro-connected hexahydropyrimidine-2,4,6-trione heterocyclic rings have received increasing attention from the viewpoint of biological activity and synthetic methods due to the importance of the rigid heterocyclic system and unique orientation of the functional substituents. Since 1900, numerous studies have exploited the synthesis of various spirobarbiturate-fused carbo- and heterocycles by applying different strategies. Due to the importance of barbiturate-based olefins as activated alkenes, these substrates have been utilized in many reactions. In addition, the nucleophilic addition of 1,3-disubstituted barbituric acid to different electrophiles has been applied to prepare highly functionalized spirobarbiturate scaffolds. This short review highlights various strategies for synthesizing spirobarbiturate-fused 3- to 7-membered carbo- and heterocyclic rings and some catalytic diastereoselective and enantioselective chemical reactions to access chiral compounds. The sections are divided by the incorporation of 3- to 7-membered heterocyclic or carbocyclic rings into a spirobarbiturate scaffold, and are presented in different subsections depending on the mechanistic details.

Recent advances in the synthesis of cyclic compounds using α,α-dicyanoolefins as versatile vinylogous nucleophiles.

α,α-Dicyanoolefins are utilized in a wide range of transformations for the synthesis of organic architectures. This review discusses the mechanisms, scope, and applications of the vinylogous reactions of α,α-dicyanoolefins in the synthesis of cyclic molecules, covering the literature from the last 13 years.

Synthesis of Substituted Phthalimides via Ultrasound-Promoted One-Pot Multicomponent Reaction.

In this work, a novel strategy for the straightforward synthesis of substituted phthalimides is described, which includes base-mediated Michael addition/intramolecular cyclization/[1,5]-H shift/cleavage of CS2/aromatization/nucleophilic acyl substitution reaction of 2-(4-oxo-2-thioxothiazolidin-5-ylidene)acetates and α,α-dicyanoolefines under ultrasound (US) irradiation. Some advantages of this method are as follows: having simple operation, easily accessible starting materials, chemoselective cascade process, synthetically useful yields, and green conditions by utilizing US irradiation as a source of energy and using ethanol as solvent.

Synthesis of tetracyclic pyrido-fused dibenzodiazepines via a catalyst-free cascade reaction.

An efficient, eco-friendly protocol has been described for the chemoselective synthesis of tetracyclic pyrido-fused dibenzodiazepines derivatives via catalyst-free, three-component reaction of dimedone, 1,2-diamines, 3-formylchromones, and malononitrile. The significant advantages of this cascade approach are to create two new rings and four new σ bonds containing three C-N and one C-C bond, as well as the breakdown of a C-O bond.

Synthesis of polycyclic N-heterocyclic compounds via one-pot three-component cyclization strategy.

Reported herein is an unprecedented and sequential three-component synthetic strategy for the preparation of polycyclic N-heterocyclic compounds. This synthetic protocol enabled the preparation of a series of novel nitrogen-containing pentacyclic compound under convenient conditions in excellent yields and short reaction time. The synthesized products were characterized by IR, 1H NMR, 13C NMR and mass spectra. Furthermore, the definitive structure of target compounds was confirmed by X-ray analysis.

Dipolar cycloaddition strategy for three-component synthesis of chromeno[3',4':3,4]pyrido[2,1-a]isoquinoline derivatives.

A rapid and efficient protocol to fused pentacyclic compounds, the chromeno[3',4':3,4]pyrido[2,1-a]isoquinolines, via a diastereoselective 1,4-dipolar cycloaddition reaction of isoquinoline, dialkyl acetylenedicarboxylates, and 3-acetyl coumarins, is described.

Diastereoselective synthesis of cyclohexadienes via tandem cyclization strategies.

A new protocol has been developed for the diastereoselective synthesis of 1,3-cyclohexadienes using vinyl malononitriles, dibenzalacetones and NaH as reagents in THF. This transformation is comprised of interesting steps like Michael addition, cyclization and ring-opening reactions.

A metal organic framework prepared from benzene-1,3,5-tricarboxylic acid and copper(II), and functionalized with various polysulfides as a sorbent for selective sorption of trace amounts of heavy metal ions.

Novel composites were obtained via direct assembly of polysulfides (Sx2-, X = 3, 4, 6) on the surface of a metal organic framework (MOF; type benzene-1,3,5-tricarboxylic/Cu(II). They are referred to as Sx-MOFs and were used for highly selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions. The structure of the Sx-MOFs was characterized by Raman spectroscopy, FT-IR, X-ray diffraction, and scanning electron microscopy. The Raman spectra of Sx-MOF is similar to the bare MOF and shows the MOFs structure to be well retained after Sx functionalization. The selective interaction of Sx with soft metal ions and the high surface area of MOFs resulted in excellent affinity and selectivity for ions such as Hg(II). The Sx-MOFs of type S4-MOF had the highest distribution coefficient Kd value (~107) and best extraction recovery (~100%) for Hg(II). The S4-MOF also has high selectivity in the following order: Hg(II) > > Pb(II) > Zn(II) > Ni(II) > Co(II). The binding process of the metals occurs via M-S bonding. The ions were quantified by inductively coupled plasma optical emission spectrometry (ICP-OES). The detection limit for Hg(II) is 0.13 µg L-1. The S4-MOF was applied to the extraction of trace metal ions from natural and contaminated waters and data were compared with other sorbets. The results revealed that S4-MOF is an excellent adsorbent for sorption of heavy metal ions even in the presence of the relatively high concentration of other ions. Graphical abstract A composite was synthesized via direct assembly of polysulfides (Sx2-, X = 3, 4, 6) on surface of the metal organic framework (Sx-MOF) and was used for selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions.

Palladium-catalyzed, unsymmetrical homocoupling of thiophenes via carbon-sulfur bond activation: a new avenue to homocoupling reactions.

The Pd-catalyzed, CN-directed unsymmetrical synthesis of 2,4'-bithiophenes via an unprecedented homocoupling reaction is described. The NH2/CN/SMe arrangement breaks the routine. The cooperative performance of the functional groups in thiophenes would open up a new vision in the field of metal catalysis homocoupling reactions by joining the electrophilic and nucleophilic motifs of the substrate. Furthermore, it is found that the α-chelating effect of the carbonyl group in amino thiophene offers a new class of synthetic protocols for C-N cross-coupling with arylboronic acids. The bidentate N,O-chelation provides a series of advantages such as copper-catalyzed, ligand- and base-free under open-flask conditions. Interestingly, the combination of the C-N cross-coupling/homocoupling reactions in a domino fashion led to the bithiophene adducts featuring the C(Ar)-N bond cleavage in the nitrogen that bridged between the two thiophene units.

Synthesis of heterocyclic [3.3.3]propellanes via a sequential four-component reaction.

A highly chemoselective heteroannulation protocol for the synthesis of unreported polysubstituted heterocyclic [3.3.3]propellanes has been developed by sequential four-component reaction of ninhydrin, malononitrile, primary amines, and dialkyl acetylenedicarboxylates under mild conditions in water. To the best of our knowledge, there are no previous reports for the synthesis of these classes of heterocyclic [3.3.3]propellanes. The merit of this sequential Knoevenagel condensation/enamine formation/Michael addition/cyclization sequence is highlighted by its high atom-economy, excellent yields, the use of water as reaction media, and the efficiency of production without the use of any activator or metal promoters. This synthesis serves as a nice addition to group-assistant-purification (GAP) chemistry in which purification via chromatography and recrystallization can be avoided, and the pure products were obtained simply by washing the crude products with 95% ethanol.

Chemoselective and one-pot synthesis of novel coumarin-based cyclopenta[c]pyrans via base-mediated reaction of α,ß-unsaturated coumarins and ß-ketodinitriles.

In this paper, the base-mediated cascade reactions of 4-chloro-3-vinyl coumarins with ß-ketodinitriles were demonstrated, allowing the efficient synthesis of coumarin-based cyclopenta[c]pyran-7-carbonitriles with interesting chemoselectivity. These transformations include the domino-style formation of C-C/C-C/C-O bonds through a base-mediated nucleophilic substitution, Michael addition, tautomerization, O-cyclization, elimination, and aromatization. The presented synthetic strategy has many advantages such as simple and readily available starting materials, green solvent, highly chemoselective route, synthetically useful yields, and easy purification of products by washing them with EtOH (96%), described as GAP (Group-Assistant-Purification) chemistry.

Correction: Chemoselective and one-pot synthesis of novel coumarin-based cyclopenta[c]pyrans via base-mediated reaction of α,ß-unsaturated coumarins and ß-ketodinitriles.

[This corrects the article DOI: 10.1039/D2RA00594H.].

An expedient metal-free cascade route to chromonyl diene scaffolds: thermodynamic vs. kinetic control.

A piperidine-catalyzed reaction between 3-formylchromone, 1,3-dimethyl barbituric acid, and ylidenemalononitriles is developed that offers chromonyl diene products in good yields. This cascade reaction proceeds via the insertion of ylidenemalononitriles between the Knoevenagel adduct obtained from 3-formylchromone and 1,3-dimethylbarbituric acid, where the pyrimidine-based enaminone is integrated with the chromone through the central diene linker. Similarly, introducing pyrimidine-based enaminone into the terminal part of the chromonyl diene scaffold gave an equilibrium mixture of rotational isomers in DMSO, which could be separated and isolated by crystallization. The computational analysis confirmed the role of barbiturate in directing the type of final chromonyl diene via kinetic or thermodynamic control. Moreover, computations revealed that one of these species, observed in the NMR spectra, is produced by the bond cleavage in the spirocyclic intermediate.

Novel approach to 1,5-benzodiazepine-2-ones containing peptoid backbone via one-pot diketene-based Ugi-4CR.

An efficient and simple route for preparation of substituted 1,5-benzodiazepine-2-one containing peptoid backbone is presented. The classical Ugi reaction is considerably extended by application of o-phenylenediamine and diketene as amine and oxo component. 1,3-Dihydro-1,5-benzodiazepine-2-one is generated in situ from these two building blocks combined with isocyanide and aromatic or aliphatic carboxylic acid to assemble the multifunctionalized titled scaffold in high yields. The reaction is performed in the mixture of toluene/CH(2)Cl(2) under reflux condition without catalyst. Conformational isomerism is seen in the solution phase because of restricted free rotation around amide and C-CO bands due to steric bulk of substitutions. In single crystal state, the product is found to possess dimeric structure arising from intermolecular hydrogen bonding.

Novel three-component route to diastereoselective synthesis of trisubstituted vinylphosphonates using phosphites, acetylenic esters, and aroyl chlorides.

Trisubstituted vinylphosphonates have been prepared via three-component reaction using phosphites, acetylenic esters, and aroyl chlorides in good yields. A variety of phosphites, activated acetylenes, and aroyl chlorides have been successfully employed in these reactions. In addition, three-component synthesis of vinylphosphonate provides exclusive E-olefin stereochemistry.

Two-Step Physical Deposition of a Compact CuI Hole-Transport Layer and the Formation of an Interfacial Species in Perovskite Solar Cells.

A simple and practical approach is introduced for the deposition of CuI as an inexpensive inorganic hole-transport material (HTM) for the fabrication of low cost perovskite solar cells (PSCs) by gas-solid phase transformation of Cu to CuI. The method provides a uniform and well-controlled CuI layer with large grains and good compactness that prevents the direct connection between the contact electrodes. Solar cells prepared with CuI as the HTM with Au electrodes displays an exceptionally high short-circuit current density of 32 mA cm(-2) , owing to an interfacial species formed between the perovskite and the Cu resulting in a long wavelength contribution to the incident photon-to-electron conversion efficiency (IPCE), and an overall power conversion efficiency (PCE) of 7.4 %. The growth of crystalline and uniform CuI on a low roughness perovskite layer leads to remarkably high charge extraction in the cells, which originates from the high hole mobility of CuI in addition to a large number of contact points between CuI and the perovskite layer. In addition, the solvent-free method has no damaging side effect on the perovskite layer, which makes it an appropriate method for large scale applications of CuI in perovskite solar cells.

Uncatalyzed one-pot synthesis of highly substituted pyridazines and pyrazoline-spirooxindoles via domino SN/condensation/aza-ene addition cyclization reaction sequence.

A previously unknown class of highly substituted pyridazines and pyrazoline-spirooxinoles are easily prepared by an uncatalyzed one-pot three-component approach incorporating a domino SN/condensation/aza-ene addition cyclization reaction sequence. 1,1-Dihydrazino-2-nitroethylene (DHNE) which is generated in situ from the nucleophilic substitution (SN) reaction of hydrazine and 1,1-bis(methylthio)-2-nitroethylene (BMTNE), allowed to be condensed with active 1,2-dicarbonyl compounds followed by an intramolecular aza-ene addition cyclization to obtain the titled products depending on the type of 1,2-dicarbonyl. All reactions are easily performed and proceed with high efficiency under very simple and mild conditions without any catalyst and give good yields avoiding time-consuming, costly syntheses, and tedious workup and purification of products.

Design, engineering and preparation of a multi-domain fusion vector for gene delivery.

Peptide based gene carriers are among the most promising non-viral vectors for gene delivery to eukaryotic cells. We have engineered a new fusion peptide using recombinant technology with the purpose of overcoming the cell barriers to gene delivery. A His- tagged multi-domain peptide was expressed in Escherichia coli BL21 (DE3) pLysS and purified using Ni-NTA resin. The fusion peptide is composed of two repeats of truncated histone H1 peptide to condense pDNA, a fusogenic peptide to disrupt endosome membranes and a nuclear localization signal to enhance translocation of pDNA towards nucleus. The results demonstrated that the vector can effectively condense plasmid DNA into nanoparticles with average sizes of 200 nm. The fusogenic peptide in the vector structure also showed membrane disruptive effect in the endosomal pH. Overall, the transfection efficiency of the vector demonstrated that it holds great promise as a nontoxic and effective non-viral gene carrier.