Formal [2+1] Annulation (Spiro-Cyclopropanation) Reaction between Sulfur Ylides Derived from Baylis-Hillman Bromides and Arylidene Indane-1,3-Dione

Pyridinium Ylide-Mediated Diastereoselective Synthesis of Spirocyclopropanyl-pyrazolones via Cascade Michael/Substitution Reaction

We have devised a highly diastereoselective formal [2 + 1] annulation reaction of arylidene/alkylidine-pyrazolones with in situ-generated supported as well as standard pyridinium ylides to construct spirocyclopropanyl-pyrazolones. The cascade approach exhibits a wide range of functional group tolerance, gram-scale capability, and substrate versatility. A diverse range of spirocyclic cyclopropanes was synthesized extensively with both mediators, and the supported pyridine was reused in subsequent cycles. Density functional theory calculations confirmed the formation of spirocyclopropane as the lower energy pathway.

Synthesis of α-pyrones via gold-catalyzed cycloisomerization/[2 + 1] cycloaddition/rearrangement of enyne-amides and sulfur ylides

A novel gold-catalyzed cycloisomerization/[2 + 1]cycloaddition/rearrangement of enyne-amides and sulfur ylides is reported. This strategy enables rapid and efficient construction of a series of α-pyrone derivatives.

Investigation of the corrosion inhibition potentials of some 2-(4-(substituted)arylidene)-1H-indene-1,3-dione derivatives: density functional theory and molecular dynamics simulation

Background

Corrosion is a threat to material strength and durability. Electron-rich organic inhibitor may offer good corrosion mitigation potentials. In this work, anti-corrosion potentials of nine derivatives of 1H-indene-1,3-dione have been investigated using density functional theory (DFT) approach and molecular dynamics (MD) simulation. Chemical reactivity descriptors like energies of lowest unoccupied molecular orbital (ELUMO), highest occupied molecular orbital (EHOMO), electron affinity (A), ionization potential (I), energy gap (ΔEgap), global hardness (η), global softness (σ), electronegativity (χ), electrophilicity (ω), number of transferred electrons (ΔN) and back-donation (ΔEback-donation) were computed at DFT/B3LYP/6-31G(d) theoretical level. The local reactive sites and the charge partitioning on the compounds were studied using Fukui indices and molecular electrostatic potential (MEP) surface analysis. The adsorption behavior and the binding energy of the inhibitors on Fe (110) surface in hydrochloric acid solution were investigated using MD simulation.

Results

The high chemical reactivity, kinetic instability and good corrosion inhibition potentials demonstrated by the inhibitors are rationalized based on their high EHOMO, A, σ, ΔN, ΔEback-donation, and low ΔEgap, ELUMO, I and η. A wide difference of approximately 2.4–3.2 eV between the electronegativities of iron and the 1H-inden-1,3-diones suggests good charge transfer tendency from the latter to the low-lying vacant d-orbitals of iron. The heteroatoms (O and N) and the aromatic moieties are the nucleophilic sites on the inhibitors for effective adsorption on the metal surface as shown by condensed Fukui dual functions and MEP analysis. The MD simulation shows good interaction and strong binding energy between the inhibitor and Fe (110) surface.

Conclusions

Effective surface coverage and displacement of H3O+, Cl− and water molecules from Fe (110) surface by the inhibitors indicate good corrosion inhibition properties of the inden-1,3-diones. 2-((4,7-dimethylnaphthalen-1-yl)methylene)-1H-indene-1,3(2H)-dione display low energy gap, strongest binding interaction and most stabilized iron-inhibitor configuration, hence, the best anti-corrosion potential.

Graphical abstract

Highly diastereoselective spiro-cyclopropanation of 2-arylidene-1,3-indanediones and dimethylsulfonium ylides

High diastereoselectivity, mild conditions and excellent functional group compatibility.

Annulations involving 2-arylidene-1,3-indanediones: stereoselective synthesis of spiro- and fused scaffolds

Stereoselective annulations of 2-arylidene-1,3-indanediones towards spiro-carbocycles as well as spiro/fused heterocycles based on various cycloadditions and tandem annulations are described.

Protecting group-directed annulations of tetra-substituted oxindole olefins and sulfur ylides: regio- and chemoselective synthesis of cyclopropane- and dihydrofuran-fused spirooxindoles

Protecting group-controlled regio- and chemoselective synthesis of cyclopropane- and dihydrofuran-fused spirooxindoles containing vicinal quaternary carbon centers.