iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A 2025 reaction converts selected isoquinolinium and pyridinium salts into three-dimensional, nitrogen-containing cage molecules by forming two rings and four bonds in one operation. Patra and colleagues report two routes—a (4 + 2) or a (3 + 2) annulation—depending on substrate design. The method is selective in demonstrated examples, but requires activated pyridinium partners and has a restricted choice of nucleophile.
How the cascade turns flat salts into caged amines
The study pairs an isoquinolinium salt with a pyridinium salt. These azolium salts have complementary reactivity: one partner supplies nucleophilic character while the other acts as an electrophile. Their reaction enables both heteroaromatic systems to lose aromaticity, or undergo dearomatization, as the fused, three-dimensional cage framework forms. The products are tertiary amines.
The authors describe an intermolecular double-dearomative cascade. Depending on the structures of the starting materials, the key ring-forming event follows either a (4 + 2) or a (3 + 2) annulation. In selected examples, the cascade creates contiguous stereocentres and proceeds with high regio- and diastereoselectivity. These are reported outcomes for the tested substrates, not a guarantee for every possible pairing.
What conditions and yields did the authors report?
For the optimized model reaction, the authors combined isoquinolinium salt 1a (0.24 mmol), pyridinium salt 2a (0.20 mmol), and sodium carbonate (0.40 mmol) in ethanol (1.5 mL). They stirred the mixture under nitrogen at room temperature for 12 hours and isolated the product in 83% yield. These are the reported conditions for that model substrate pair, not universal instructions for all substrates.
#1 Best Overall
- FOR BASIC TEACHING TO ADVANCED SCIENCE: 444 pieces molecular model kit, including 136 atoms, 158 bonds and 150 parts for Carbon-60(Fullerene), provides to students from Grade 7 to Graduate level.
- TWO CHEMICAL STRUCTURE MODELS: The ball-and-stick models use spheres to represent atoms and sticks to represent chemical bonds. In the space-filling model, the spheres are drawn to scale and are next to one another as atoms are in real molecules.
- CHEMISTRY EDUCATIONAL MOLECULE MODEL IN 3D: It can display chemical structure, molecular bond, and bond angle in all directions. Demonstrate fundamental molecular geometry, chemical molecular structure, stereochemistry with 3D modeling studies.
- EASY TO LEARN: The universal standard adopted for each atom's color makes it easier for you to use and learn. Atoms and chemical bonds combine tightly and firmly and can be easily disassembled by disconnecting tools.
- If you’re not in love with it for whatever reason, we’ll give you a full replacement or refund—no questions asked. If you have any doubt, please tell us. With nothing to worry about, or even to share with your friends, try it now.
Changing the reaction time or temperature affected the model reaction: 30 hours at room temperature gave 36%, while heating to 80 °C gave 70%. Solvent and base substitutions also changed yields. The comparison illustrates why the 83% result should be tied to its specific optimized conditions rather than treated as a general expected yield.
Which substrate designs worked—and where does the method stop?
Demonstrated pyridinium partners
A range of N-benzyl pyridinium analogues bearing different aryl substituents gave products in 70–77% yields. N-methyl, N-ethyl, N-butyl, and N-allyl pyridinium salts also participated, as did a 3-nitropyridinium salt. The paper highlights high regio- and diastereoselectivity for its (4 + 2) examples.
Rank #2
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 444 Pcs Complete Set: The atom model kit includes with 136 atoms,158 bonds, and 150 fullerene model parts, explore most the molecules structures from simple compounds to complex polymers.
- Effortless Assembly: Embedded component design ensures easy to construct Ball-and-stick and Space-filling models that maximizes focus on exploration without complex assembly.
- Durable & Portable: Built to last, the chemistry set is crafted from high-quality materials. Plus, its portable Snap-Lock design allows you to take your experiments learning anywhere, between the home, classroom and lab.
- Essential Study Tool: Whether you're studying organic chemistry, biochemistry, or molecular biology, molecule building kit is an perfect learning tool for you deeper comprehension of molecular science.
Activation is an important boundary: the parent pyridinium salt without an activating group did not give the desired cage. The reported success therefore applies to selected, activated pyridinium salts, not pyridinium salts generally.
The alternate (3 + 2) route and larger demonstrations
Substrate design also enabled a (3 + 2) pathway. A 4-hydroxy-substituted isoquinolinium example produced the cage in 70% yield as a single diastereomer; a minor regioisomer was reported at 14%.
Rank #3
- UNLOCK YOUR CHEMISTRY POTENTIAL: Our comprehensive molecular model kit includes 238 pieces, featuring 84 atoms, 153 bonds and a remover tool. Suitable for chemistry learners from beginners to advanced levels. Manufacturer recommended age: 15 years and up
- ORGANIZED STORAGE AND EASY LOCATING: Experience hassle-free organization with our storage box, complete with divided compartments and labeled sections. Say goodbye to clutter and quickly find the components you need
- EXTRA LEARNING MATERIALS FOR EXCELLENCE: Enhance your studies with our bonus 6-page learning guide and stencils. From grade 9 to college, from organic to inorganic, finish and master your assignments faster and create numerous molecular structures with ease
- IMMERSIVE 3D VISUAL LEARNING: Explore chemistry in a captivating way with our 3D visual learning approach. The universal color-coded Atomic Balls provide a better understanding of molecular structure, boosting your chemistry knowledge. It's also a perfect gift for someone who are going to learn those complex molecule
- EASY-TO-USE DESIGN: Crafted from smooth, burr-free plastic, our molecular science kit ensures easy assembly. With the included remover tool, disassembling is a breeze
The authors also report a five-component, one-pot sequence that gave a model product in 71% yield without loss of the reported selectivity. A gram-scale reaction gave 75% yield as a single diastereomer, with regioselectivity greater than 10:1. These results demonstrate feasibility for those examples; they do not establish industrial-scale performance.
Nucleophile compatibility is a constraint
The nucleophile is introduced at the final stage, but it must not react prematurely with the highly electrophilic azolium salts. Study leader Mahiuddin Baidya described this as a restriction on the nucleophile choice in a Chemistry World report. The reported work does not establish broad nucleophile or functional-group tolerance beyond the substrates tested.
Rank #4
- ADVANCED LEARNING SCIENCE EDUCATION KIT --- Perfect chemistry model kit for modeling simple and small to more advanced and complex chemical structures for schools and college level, students of all ages, researchers and enthusiasts. Fun and interactive early learning molecular set for kids of all years and for use in the classroom.
- HIGH QUALITY --- Made from high quality durable materials designed for easy construction and perfect fit. These Molecular Model Kit pieces are color coded to national standards for easy ID. Organic Chemistry Model Kit includes box for easy storage and transport with your other textbooks, notes, and books. Excellent for the classroom.
- POWERFUL FUNCTIONS --- This Molecular Model Kit has a total of 136 pieces including short link remover tool. Super easy to build models for organic and inorganic chemistry, This model contains C, H, O, N, S and a variety of single and double bonds, Can be put high school, university chemistry in most of the organic or inorganic molecular structure model for the study of experimental operation.
- QUICK AND EASY ASSEMBLY OF COMPLEX STRUCTURES --- Atoms and bonds that are perfectly suited to being connected and disconnected easily without making your fingers hurt. We've also included a link remover to make the task of easy.
- CONVENIENT STORAGE --- The pieces come in a slim plastic box for convenient storage. See the pictures on this listing for a full understanding of what's inside
What mechanism do the authors propose?
The proposed sequence begins when base generates an enolate from the isoquinolinium salt. That intermediate reacts with the pyridinium salt, then undergoes intramolecular annulation and subsequent nucleophile trapping to furnish the cage. The authors’ density functional theory calculations identify annulation as the rate-limiting part of the proposed sequence. In their computational account, the (4 + 2) annulation is stepwise, while the (3 + 2) pathway is concerted. This is the authors’ computationally supported mechanistic proposal, not an independently established experimental account.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCrashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteDoes the study show that the cages have drug potential?
No biological activity or therapeutic use is established for the new compounds in the cited reports. The authors’ motivation is that three-dimensional, heteroatom-containing frameworks could expand chemical space for drug discovery and functional materials. Baidya told Chemistry World that reducing the number of two-dimensional aromatic systems in a molecule could improve its chance of showing biological activity; that is his rationale for the work, not a result from testing these cages.
Best Value
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 240 Pcs Complete Set: The atom model kit includes with 86 atoms and 154 bonds, explore most the molecules structures from simple compounds to complex polymers.
- Effortless Assembly: Embedded component design ensures easy to construct Ball-and-stick and Space-filling models that maximizes focus on exploration without complex assembly.
- Durable & Portable: Built to last, the chemistry set is crafted from high-quality materials. Plus, its portable design allows you to take your experiments learning anywhere, between the home, classroom and lab.
- Essential Study Tool: Whether you're studying organic chemistry, biochemistry, or molecular biology, molecule building kit is an perfect learning tool for you deeper comprehension of molecular science.
Pharmaceutical chemist Laura Ielo said she had not encountered these scaffolds in pharmaceutical applications and would begin by conducting biological assays and computational investigations to assess their potential. Those follow-up evaluations are not reported in the cited sources. The supported claim is therefore synthetic: the reaction makes new caged amine frameworks that could be investigated, not demonstrated drug candidates.
What the study establishes
Patra, Deb, Choutipalli, Mulani, Mallik, Subramanian, and Baidya reported the work as “Transforming 2D azolium salts to 3D caged tertiary amines via stereoselective dearomative cascade annulation” in Chemical Science 16 (2025), pages 7551–7559. It was first published on 26 March 2025. The paper establishes a synthetic approach with two annulation modes and selective results across specific examples. Its boundaries—especially the need for activated pyridinium partners and compatible nucleophiles—matter when considering what the method can make.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →
