Quantum-Chemical Insight into Self-Organization of Complex Molecules from Acetylene and Anilines Catalyzed by Superbase KOH/DMSO: One-Pot Cascade Assembly of 1,3-Bis(arylamines)

The self-organization of functionalized diamines, 1-acetyl-1,3-bis(haloarylamines), from three molecules of acetylene and two molecules of haloanilines in the KOH/DMSO superbase medium, has been analyzed quantum chemically in some detail in the framework of the B2PLYP(D3)/6-311+G**//B3LYP/6-31+G* approach. We have established that the diamines are constructed in a cascade manner via the sequential alternating additions of haloaniline anions to acetylene. The reaction sequence is catalyzed by a superbase pentacoordinated complex, KOH center dot 5DMSO, where the hydroxide ion is significantly separated from the potassium cation (the K-OH bond length is by 0.4-0.5 angstrom longer than in the bare KOH molecule). The latter imparts pronounced superbasicity to the complex and provides for a shuttle-like proton transfer (H++OH-=H2O) during the whole cascade process.