Yen-Pon, Expedite; Buttard, Floris; Frederic, Lucas; Thuery, Pierre; Taran, Frederic; Pieters, Gregory; Champagne, Pier Alexandre; Audisio, Davide published an article in 2021. The article was titled 《Heterohelicenes through 1,3-Dipolar Cycloaddition of Sydnones with Arynes: Synthesis, Origins of Selectivity, and Application to pH-Triggered Chiroptical Switch with CPL Sign Reversal》, and you may find the article in JACS Au.SDS of cas: 128071-75-0 The information in the text is summarized as follows:
Regioselective access to heterohelicenes through the 1,3-dipolar cycloaddition of sydnones with arynes was described. Novel access to sydnones and poly(hetero)aromatic aryne precursors allowed the introduction of chem. diversity over multiple positions of the helical scaffolds. The origins of the unconventional regioselectivity during the cycloaddition steps was systematically investigated using d. functional theory (DFT) calculations, unveiling the key features that control this reactivity, namely, face-to-face (π···π) or edge-to-face (C-H···π) interactions, primary orbital interactions and distortion from coplanarity in the transition structures (TSs) of the transformation. From the library of 24 derivatives synthesized, a pyridyl containing derivative displayed reversible, red-shifted, pH-triggered chiroptical switching properties, with CPL-sign reversal. It was found that protonation of the helicene causes a change of the angle between the elec. and magnetic dipole moments related to the S1 → S0 transition, resulting in this rare case of reversible CPL sign inversion upon application of an external stimulus.2-Bromonicotinaldehyde(cas: 128071-75-0SDS of cas: 128071-75-0) was used in this study.
2-Bromonicotinaldehyde(cas: 128071-75-0) belongs to pyridine. Pyridines form stable salts with strong acids. Pyridine itself is often used to neutralize acid formed in a reaction and as a basic solvent. SDS of cas: 128071-75-0