Notes- Dissociation Constants of 2-Substituted Pyridines

Binding Interactions with the Complementary Subunit of Nicotinic Receptors

“…When considering closely related systems, pK a is an excellent predictor of hydro- gen bonding ability. Pyridine, a good model for nicotine, has a pK a of 5.2, but 2-chloropyridine, a model for epibatidine, has a much lower pK a of 0.5 (29). Thus, epibatidine is expected to be a poorer base than nicotine by ϳ5 orders of magnitude, and it is safe to conclude that epibatidine would also be a much poorer hydrogen bond acceptor.…”

Hydroxythiazole‐Based Fluorescent Probes for Fluoride Ion Detection

“…The other anions tested are much less effective in triggering the desilylation of 3a, indicating high selectivity towards the fluoride ion ( Figure 5). Considering the basicity of pyridine (pK aH = 5.2, pK aH DMSO = 3.5), [14] the data allowed us to confirm the formation of 5a. As expected, the Si-O bond in compound 3a was cleaved in the presence of OHanions at pH Ͼ 8, as indicated by the increase in the red fluorescence (formation of enolate 4a, Figure 6).…”

“…Data corresponding to 3 and 4 were acquired by the addition of TBAF to the former in DMSO. [14] [b] Experimental value (Supporting Information, Figure S1). The protonation of the pyridine moiety of compounds 1 has no effect on absorption and fluorescence data when comparing compounds 1 and 5.…”

Brønsted Acid Catalyzed Oxygenative Bimolecular Friedel–Crafts‐type Coupling of Ynamides

“…Ther esulting products represent pharmaceutically interesting 1,1-di(hetero)aryl core that comprises privileged scaffolds displaying diverse range of biological activity. [10] In fact, use of 2-Cl-pyridinium NTf 2 salt (10 mol %) was equally effective (entries 8a nd 9). Among various Brønsted acids tested, HNTf 2 was identified as the most suitable acid catalyst (entries 1-7).…”