ABSTRACT
The ethoxycarbonylmethyl esters of 1,4-dihydropyridines were directly converted into carbamoylmethyl esters in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in good to excellent yields under mild conditions. The use of TBD is crucial for the successful aminolysis of ethoxycarbonylmethyl ester of 1,4-dihydropyridines with secondary amines as without it the reaction does not proceed at all. The aminolysis reaction proceeded regioselectively, as the alkyl ester conjugated with the 1,4-dihydropyridine cycle was not involved in the reaction. Screening of other N-containing bases, such as triethylamine (TEA), pyridine, 4-(N,N-dimethylamino)pyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), imidazole, tetramethyl guanidine (TMG) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) as catalysts revealed no activity in the studied reaction.
Subject(s)
Amines/chemistry , Carboxylic Acids/chemistry , Dihydropyridines/chemistry , Catalysis , Dihydropyridines/chemical synthesis , Esters , Solvents/chemistryABSTRACT
New amphiphilic pyridine derivatives containing dodecyloxycarbonyl substituents at positions 3 and 5 and cationic moieties at positions 2 and 6 have been designed and synthesised. Compounds of this type can be considered as synthetic lipids. The corresponding 1,4-dihydropyridine (1,4-DHP) derivatives have earlier been proposed as a promising tool for plasmid DNA (pDNA) delivery in vitro. In this work studies of the self-assembling properties of amphiphilic pyridine derivatives leading to the formation of liposomes, determination of particle size, zeta-potential and critical micelle concentration (CMC) with dynamic light scattering (DLS) measurements are described. Furthermore, thermal analysis of pyridine derivatives was performed using thermogravimetry analysis (TGA) and differential thermal analysis (DTA) as well as the ability to deliver the pEGFP-C1 plasmid DNA (that encodes GFP reporter) into the Baby hamster kidney-derived (BHK-21) cell line was used for evaluation of gene delivery properties. We have revealed that the new pyridine derivatives possessed self-assembling properties which were proved by formation of nanoparticles with the average size from 115 to 743nm, the zeta-potentials in the range of 48-79mV and CMC values in the range of 2-67µM. DTA data showed that all processes were endothermic for all compounds. Additionally, we established that among the tested pyridines the representatives with N-methylpyrrolidinium or pyridinium moieties as cationic head-group at the positions 2 and 6 possessed higher pEGFP-C1 transfection activity into the BHK-21 cell line. Nevertheless, the obtained results indicated that correlation of the physicochemical, structural properties and gene delivery activities of the tested compounds were not completely elucidated yet. On the other hand, the synthesised pyridines as possible metabolites of promising delivery systems on the 1,4-DHP core possessed lower pDNA transfection activity than the corresponding 1,4-DHP amphiphiles.
Subject(s)
Pyridinium Compounds/chemistry , Transfection , Animals , Cations , Cell Line , Cricetinae , Dynamic Light Scattering , Genes, Reporter , Liposomes/chemistry , Micelles , Nanoparticles/chemistry , Particle Size , Plasmids/genetics , Plasmids/metabolism , ThermogravimetryABSTRACT
The diastereotopy of the methylene protons at positions 2 and 6 in 1,4-dihydropiridine derivatives with various substituents has been investigated. NMR spectroscopy and quantum chemistry calculations show that the CH···O intramolecular hydrogen bond is one of the factors amplifying the chemical shift differences in the 1H-NMR spectra.
Subject(s)
Dihydropyridines/chemistry , Dihydropyridines/chemical synthesis , Hydrogen Bonding , Magnetic Resonance Spectroscopy , Molecular Conformation , Structure-Activity RelationshipABSTRACT
Since 2,6-dimethyl-4-aryl-1,4-dihydropyridine 3,5-diesters themselves are not hydrolyzed by commercially available hydrolases, derivatives with spacers containing a hydrolyzable group were prepared. Seven acyloxymethyl esters of 5-methyl- and 5-(2-propoxyethyl) 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate were synthesized and subjected to Candida rugosa lipase (CRL) catalyzed hydrolysis in wet diisopropyl ether. A methyl ester at the 5-position and a long or branched acyl chain at C3 gave the highest enantiomeric ratio (E values). The most stereoselective reaction (E = 21) was obtained with 3-[(isobutyryloxy)methyl] 5-methyl 4-(2-difluoromethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate, and this compound was used to prepare both enantiomers of 3-methyl 5-(2-propoxyethyl) 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate. The absolute configuration of the enzymatically produced carboxylic acid was established to be 4R by X-ray crystallographic analysis of its 1-(R)-phenylethyl amide.
