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

One-pot reaction of 3-vinylchromones, aromatic aldehydes, and ammonium acetate: an efficient approach to highly functionalized 1,6-dihydropyridine derivatives

In this work, we present an efficient strategy for the straightforward synthesis of functionalized 1,6-dihydropyridine derivatives via a three-component reaction of 3-vinylchromones, aromatic aldehydes, and ammonium acetate. A tandem procedure including in situ NH aldimine formation/Michael-type addition/opening of the pyrone ring/isomerization/6π-electrocyclization/[1,5]-H shift allows rapid access to a series of dihydropyridines bearing an ortho-hydroxybenzoyl and a benzoyl scaffold in good yields. Readily available precursors, simple heating conditions, and operational simplicity are some highlighted advantages of this transformation.

Multicomponent reactions (MCRs) yielding medicinally relevant rings: a recent update and chemical space analysis of the scaffolds

In this review we have compiled multicomponent reactions (MCRs) that produce cyclic structures. We have covered articles reported since 2019 to showcase the recent advances in this area. In contrast to other available reviews on this topic, we focus specifically on MCRs with strong prospects in medicinal chemistry. Consequently, the reactions operating in a single-pot and yielding novel rings or new substitution patterns under mild conditions are highlighted. Moreover, MCRs that do not require special reagents or catalysts and yield diverse products from commercially available building blocks are reviewed. The synthetic schemes, substrate scope, and other key aspects such as regio- and stereoselectivity are discussed for each MCR. Using cheminformatic tools, we have also attempted to characterize the chemical space of the scaffolds obtained from these MCRs. We show that the MCR scaffolds are novel, more complex, and globular in shape compared to the approved drugs and clinical candidates. Thus, our review represents a step towards identifying and characterizing the novel ring space that can be accessed efficiently through MCRs in a short timeframe.

Ultrasound-promoted removal of benzylidene and isopropylidene acetal protection of carbohydrates in presence of sulfonated graphene (GR-SO3H) as a sustainable acid catalyst

Sulfonated graphene (GR-SO3H) was prepared and used as an efficient and sustainable catalyst to deprotect O-benzylidene and O-isopropylidene acetal of carbohydrates under ultrasound (US) irradiation. The solid catalyst can recovered by simple filtration and used several times without much loss in reactivity. This methodology not only reduces the reaction time but also increases the yield. Moreover, the work-up and purification procedure is very simple and also effective for large-scale preparation.

Recent trends for chemoselectivity modulation in one-pot organic transformations

In organic reactions, chemoselectivity refers to the selective reactivity of one functional group in the presence of another. This can be more successful if the reagent and reaction parameters are appropriately chosen. One-pot reactions have been shown to be an effective structural variety technique for the development of novel heterocyclic or carbocyclic compounds. This review article focuses on recent efforts by researchers from around the world to synthesise novel organic molecules utilising these methodologies (2013-2024), as well as their mechanism insights. The substrate, catalyst, solvent, and temperature conditions all have a significant impact on chemoselectivity in the organic reactions described here. The manipulation of chemoselectivity in organic processes creates new potential for the production of novel heterocycles and carbocycles.

Sulfur- and DABCO-Promoted Reaction between Alkylidene Rhodanines and Isothiocyanates: Access to Aminoalkylidene Rhodanines

In this work, an efficient sulfur- and DABCO-promoted reaction for the synthesis of aminoalkylidene rhodanines from available alkylidene rhodanines and isothiocyanates is reported. A tandem process including sulfurative annulation/ring-opening by liberation of a CS2 molecule/olefination allows the synthesis of aminoalkylidene rhodanines with acceptable functional group tolerance. Chemo- and stereoselectivity, operational simplicity, and synthetically useful yields are some highlighted advantages of these transformations.

Three-Component Reaction between 3-Acetylcoumarins, Amines, and Elemental Sulfur: A Designed Approach to 3-Amino-4H-thieno[3,2-c]coumarins

In this work, a series of novel 3-amino-4H-thieno[3,2-c]coumarins were designed and synthesized by a one-pot, catalyst-free, and three-component reaction of 3-acetylcoumarins with amines and elemental sulfur. Readily available starting materials, simple heating conditions, facile installation of a sulfur atom into the molecule using S8 as a sulfur source, acceptable functional group tolerance, and synthetically useful yields are some highlighted benefits of this process.

Two distinct protocols for the synthesis of unsymmetrical 3,4-disubstituted maleimides based on transition-metal catalysts

Two tandem catalytic systems are described for the synthesis of novel 3,4-disubstituted maleimides using the same Ugi adducts as starting materials. 4-Aryl-3-pyrrolyl- and 4-aryl-3-indolyl-maleimides were successfully obtained via a Pd(OAc)2/PPh3 based protocol. In contrast, maleimide-fused pyrrolo and indolo[1,2-a]quinolines were obtained in a complementary methodology using CuI/L-proline. These strategies involved a combination of benzylic amine oxidation, trans-amidation, intramolecular Knoevenagel condensation, and N-arylation reactions. Computational investigations provide further insights into this reaction sequence.

Ultrasound-promoted synthesis of novel N-arylamino-3,5′-biquinoline derivatives: their applications in live-cell imaging and in vitro anticancer activity evaluation

A novel strategy for the construction of functionalized N-arylamino-3,5′-biquinoline has been developed.

Recent developments in one-pot stepwise synthesis (OPSS) of small molecules

One-pot synthesis is an active topic in organic chemistry due to its intrinsic advantages of simple operation, high mass efficiency, low cost, and less amount of waste disposal. Among three kinds of one-pot syntheses, 1) cascade reactions, 2) multicomponent reactions (MCRs), and 3) one-pot stepwise synthesis (OPSS), OPSS could be more flexible and practical since it is carried out stepwisely and have variable reaction conditions for different steps. This perspective article uses selected examples to highlight the recent development in OPSS involving cyclization, cycloaddition, rearrangement, and catalytic reactions for the synthesis of heterocyclic scaffolds, asymmetric molecules, natural products, and bioactive compounds.

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

This article provides a review of the applications of α,α-dicyanoolefins as versatile vinylogous nucleophiles in the synthesis of various cyclic compounds, covering the literature from the past 13 years.

Adamantane-Functionalized Phthalimide Scaffold: Pathways to Supramolecular Interactions and Drug Discovery

Herein, the synthesis of a novel adamantanyl-functionalized phthalimide scaffold is demonstrated. The novel compound could be used as a precursor for various synthetic pathways owing to the generic use of adamantane substituents as the driving force for supramolecular interactions with macrocycles and N-substituted phthalimide derivatives as a core structure in numerous drugs. The adamantanyl-functionalized phthalimide scaffold contains bromide groups on the C4 and C5 positions of the benzene ring, effectively allowing further facile modifications of the scaffold. The structure was fully characterized including single-crystal X-ray crystallography. The crystal structure shows an adamantane moiety at an angle of 115.57(7)° to the phthalimide core, hence sterically freeing the adamantane unit for host–guest interactions.

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.