Bromination of 4-aryl-3,5-dialkoxycarbonyl-2,6-dimethyl-1,4-dihydropyridines

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

“…Substitution reactions were performed at room temperature due to the fact that at temperatures above 50 1C lactonisation of 2,6-di(bromomethyl) substituted 1,4-DHP 3 to 8-phenyl-5,8-dihydro-1H,3H-difuro-[3,4-b:3 0 ,4 0 -e]pyridine-1,7(4H)-dione occurs. 34 Fig. 1 General composition of the structure of cationic lipids 21 (A); structure of cationic 1,4-dihydropyridine amphiphile 1 (B).…”

Experimental and Theoretical Studies of Bromination of Diethyl 2,4,6‐Trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate

“…N ‐Bromosuccinimide (NBS) is a widely used as a brominating as well as a mild and selective oxidizing agent for many classes of organic compounds. It has been reported by our laboratories that bromination of methyl groups at the positions 2 and 6 of Hantzsch‐type N‐unsubstituted and N‐substituted 2,6‐dimethyl‐4‐aryl‐1,4‐dihydropyridine‐3,5‐dicarboxylates in methanol at room temperature leads to the formation of various brominated products in good yields, depending on the amount and type of halogenation reagent .…”

“…The authors proposed the oxidation of a 1,4‐DHP ring instead of bromination of methyl groups at the positions 2 and 6 of the 1,4‐DHP ring with NBS in methanol at room temperature in 5 min . However, in our study 4‐phenyl‐, 4‐methyl‐, 4‐(3‐nitrophenyl)‐, 4‐(2‐difluoromethoxyphenyl)‐, 4‐(2‐trifluormethylphenyl)‐, and 4‐(3,4,5‐trimethoxyphenyl)‐substituted diethyl 2,6‐dimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylates with NBS in methanol at room temperature formed exclusively 2‐bromomethyl‐ or/and 2,6‐bis(bromomethyl)‐1,4‐DHP derivatives with no evidence of formation of the corresponding oxidized products and these results have been published in several articles . This discrepancy prompted us to investigate closely the mechanism of bromination of 1,4‐DHPs with NBS in methanol.…”

Intramolecular C-H···O Hydrogen Bonding in 1,4-Dihydropyridine Derivatives

“…In recent years many studies attempting to modify the 2,6-methyl groups of 1,4-DHP by introducing various substituents have been performed [ 3 , 4 , 5 , 6 ]. On the other hand cationic amphiphilic 1,4-DHP derivatives have gained significance as useful transport molecules for the delivery of nucleotides into target cells [ 4 , 7 ].…”