Equilibrium NH-acidity of 1,4-dihydropyridines and 4,5-dihydroindeno[1,2-b]pyridines

Gene delivery agents possessing antiradical activity: self-assembling cationic amphiphilic 1,4-dihydropyridine derivatives

“…For Hantzsch type 2,6-dimethyl-1,4-dihydropyridine-3,5dicarboxylates, structurally related to parent 1,4-DHP derivatives 2 and 3, the pK a value is considered to be approximately 20. 56 We have, however, demonstrated that 1,4-DHP amphiphile 1 and related derivatives with varying lengths of alkyl chains at positions 3 and 5 and pyridinium as the head-group at positions 2 and 6 show buffering capacity in the pH range of 6-8 and have the pK a value approximately at pH 7. 19 Deprotonation of the N-H group of the 1,4-DHP ring is caused by the proximity of positively charged substituents at positions 2 and 6 of the 1,4-DHP ring.…”

Direct photolysis of 4-tert-alkyl-1,4-dihydropyridines under blue-light irradiation for the generation of tertiary alkyl radicals

“…Prior work by Dubur and coworkers demonstrated that the NH acidity of DHPs is heavily influenced by the substituents at the C3 and C5 positions (Table 2). 25 If CN groups are located at C3 and C5 (1), the pKa of the DHP was determined to be 16.7, whereas the pKa increases to 20.1 if the DHP contains CO2Et groups (23). By comparing the initial rates of both corresponding 4-tert-butyl-DHPs, we see an eleven-fold faster rate for 1.…”

Direct photolysis of 4-tert-alkyl-1,4-dihydropyridines under blue-light irradiation for the generation of tertiary alkyl radicals

“…Prior work by Dubur and co-workers demonstrated that the NH acidity of DHPs is heavily influenced by the substituents at the C3 and C5 positions (Table 2). 25 If CN groups are located at C3 and C5 ( 1 ), the p K a of the DHP was determined to be 16.7, whereas the p K a increases to 20.1 if the DHP contains CO 2 Et groups ( 23 ). By comparing the initial rates of both corresponding 4- tert -butyl-DHPs, we see an eleven-fold faster rate for 1 .…”