Step Forward to Stronger Neutral Organic Superbases: Fused Troponimines

• Published in: Journal of organic chemistry 2020-09, Vol.85 (17), p.11375-11381
• Main Authors: Saadat, Kayvan, Shiri, Ali, Kovačević, Borislav
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.0c01466

In this study, using a computational approach, we are pursuing to find a proper answer about the possible application of fused TIs as superbases through the calculation and discussion of standard thermochemistry parameters, like gas-phase basicity (GB) and proton affinity (PA). In some studied cases, the role of aromaticity/antiaromaticity fluctuations supposed to be more important than mesomeric effects. In this sense, nucleus-independent chemical shift (NICS) and anisotropy of the induced current density (ACID) were utilized in this study to probe into the aromaticity-related parameters of the proposed molecules. Results revealed the highest GB/PA values for the molecules having cyclobutadiene in between two troponimines. Additional investigation was performed into the other candidates of cyclobutadiene-fused troponimines by substituting several electron donors along with the changing position of donors. Some novel superbases offered record-holding GB/PA values so that PA magnitudes higher than 300 kcal mol–1 are now feasible for nonphosphorous neutral organic superbases (NOS).