研究目的
To identify substitution patterns on chiral thiophene S-oxides that lead to stable atropisomers at room temperature by investigating pyramidal inversion barriers using quantum chemical methods.
研究成果
The B3LYP-D3 functional provides accurate inversion barriers. Electron-donating substituents increase barriers, while electron-withdrawing groups decrease them. Aromaticity changes are a key factor, with higher barriers correlating with larger aromaticity differences. This enables the design of stable chiral thiophene S-oxides for atroposelective synthesis.
研究不足
The study is theoretical and computational, lacking experimental validation. Solvent effects were modeled with continuum solvation models, but explicit solvation might be needed for accuracy. The focus is on specific thiophene derivatives, and generalizability to other systems may be limited.
1：Experimental Design and Method Selection:
The study uses density functional theory (DFT) and wave function methods to compute pyramidal inversion barriers of thiophene S-oxides. A benchmark study evaluated various functionals (e.g., B3LYP-D3, M11) against CCSD(T) reference data.
2：Sample Selection and Data Sources:
A large set of thiophene S-oxide derivatives with different substituents (e.g., alkyl, electron-donating, electron-withdrawing groups) were selected based on literature and synthetic feasibility.
3：List of Experimental Equipment and Materials:
Computational software (Gaussian 09, Molpro.
4：1) and basis sets (cc-pVTZ, aug-cc-pVTZ) were used. No physical equipment is mentioned. Experimental Procedures and Operational Workflow:
20 Geometries were optimized using DFT, and potential energy surfaces were computed by varying the C-C-S-O dihedral angle. Frequency calculations confirmed minima and transition states. Aromaticity indices (HOMA, NICS) and noncovalent interactions (NCI index) were analyzed.
5：Data Analysis Methods:
Statistical errors (MUE, RMSD) were calculated relative to CCSD(T). Correlations between inversion barriers and aromaticity changes were assessed.
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