A new approach for the solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepines involving reductive cleavage

A methodology based on reductive cleavage followed by cyclization, for the solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepines employing DIBAL-H, is described.     

Spectro Analytical,Computational and In Vitro Biological Studies of Novel Substituted Quinolone Hydrazone and it’s Metal Complexes

Some novel transition metal [Cu (II), Ni (II) and Co (II)] complexes of nalidixic acid hydrazone have been prepared and characterized by employing spectro-analytical techniques viz: elemental analysis, ¹H-NMR, Mass, UV–Vis, IR, TGA-DTA, SEM-EDX, ESR and Spectrophotometry studies. The HyperChem 7.5 software was used for geometry optimization of title compound in its molecular and ionic forms. Quantum mechanical parameters, contour maps of highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) and corresponding binding energy values were computed using semi empirical single point PM3 method. The stoichiometric equilibrium studies of metal complexes carried out spectrophotometrically using Job’s continuous variation and mole ratio methods inferred formation of 1:2 (ML₂) metal complexes in respective systems. The title compound and its metal complexes screened for antibacterial and antifungal properties, exemplified improved activity in metal complexes. The studies of nuclease activity for the cleavage of CT- DNA and MTT assay for in vitro cytotoxic properties involving metal complexes exhibited high activity. In addition, the DNA binding properties of Cu (II), Ni (II) and Co (II) complexes investigated by electronic absorption and fluorescence measurements revealed their good binding ability and commended agreement of K_b values obtained from both the techniques. Molecular docking studies were also performed to find the binding affinity of synthesized compounds with DNA (PDB ID: 1N37) and “Thymidine phosphorylase from E.coli” (PDB ID: 4EAF) protein targets.     

Synthesis and Antibacterial Evaluation of Benzofuran Based Di-1,2,3-triazoles

Russian Journal of General Chemistry - A series of novel benzofuran-1,2,3-triazole hybrid molecules are synthesized using the click chemistry approach. Structures of the synthesized compounds were...     

Synthesis,characterization and biological evaluation of purine nucleoside analogues

We present a convenient route for the synthesis of C6-amino-C5′-N-cyclopropyl carboxamido-C2-alkynylated purine nucleoside analogues 11a–g via Sonogashira coupling reaction. The nine step synthesis is easy to perform, employing commercially available reagents. Compound 9 is used as key intermediate for the synthesis of analogues 11a–g. Synthetic intermediates and final products are appropriately characterized by IR, ¹H NMR, ¹³C NMR and Mass. The modified nucleoside analogues 11a–g is evaluated for in vitro anticancer activity against MDA-MB-231 and Caco-2 cell lines. Screening data reveals that compounds 11b and 11e displayed potent IC₅₀ value of 7.9, 6.8 µg/mL respectively against MDA-MB-231 and of 7.5, 8.3 µg/mL respectively against Caco-2 than the standard drug doxorubicin, thus establishing the potential anti-cancer properties of these newer derivatives.     

Free radical 5-exo-dig cyclization as the key step in the synthesis of bis-butyrolactone natural products: experimental and theoretical studies

Radical cyclization reactions were performed by 5-exo-dig mode to yield cis-fused bicyclic systems, leading to the synthesis of bis-butyrolactone class of natural products. The study was aimed at understanding the impact of alkyl side chains of furanoside ring systems in L-ara configuration on the radical cyclization. It was amply demonstrated by experimental studies that the increase in the length of the alkyl side chain has an effect on the cyclization: while efficient cyclization reactions could be realized with methyl and ethyl side chains, the yields were significantly reduced in the case of n-pentyl side chain. Theoretical studies using DFT and (RO)MP2 methods were carried out to analyze the influence of the substitution pattern on the cyclization barriers.     

A one-pot azido reductive tandem mono-N-alkylation employing dialkylboron triflates: online ESI-MS mechanistic investigation

An efficient one-pot reductive tandem mono-N-alkylation of both aromatic and aliphatic azides using dialkylboron triflates as alkylating agents has been examined under standardized reaction conditions. This methodology after optimization has been employed toward the syntheses of various secondary alkyl as well as aryl amines, including the synthesis of N10-butylated pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones via in situ azido reductive-cyclization process. This protocol is particularly attractive to provide an environmentally benign and practical method for mono-N-alkylation from organic azides without the use of toxic catalysts or corrosive alkylating agents. In addition, the mechanistic aspects have been investigated and the intermediates associated with this selective transformation have been intercepted and characterized by online monitoring of the reaction by ESI-MS/MS.     

Enantioselective total syntheses of ropivacaine and its analogues

An alternative asymmetric synthesis of ropivacaine and analogues employing the ‘cation pool’ strategy and host/guest supramolecular co-catalysis approach is presented. In this study, chiral auxiliaries, several soft nucleophiles as well as one-pot conditions for anodic oxidation, followed by nucleophilic addition, have been applied.     

Kumada cross coupling reaction based synthesis,antimicrobial and computational studies of 6-aryl-2-phenyl-3-methylquinazolin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

Nickel catalyzed Kumada cross coupling reaction, a novel synthetic method for the synthesis of 6-aryl-2-phenyl-3-methylquinazolin-4(3H)-ones (6a–6i), was carried out by condensing 6-iodo-2-phenyl-3-methyl-quinazolin-4(3H)-one (4) with various 6-aryl/heteroaryl Grignard reagents. Molecular properties of compounds 4 and 6a–6i were studied using semiempirical PM3 computational method. The optimized geometry of the product 6 indicated that the aryl group at the position 6 was not coplanar with respect to either quinazolinone ring or phenyl group at 2 position. Compounds 6a–6i were screened for their activity against bacteria and fungi.     

Enantioselective total synthesis of (S)-(+)-lennoxamine through asymmetric hydrogenation mediated by l-proline-tetrazole ruthenium catalyst

A novel asymmetric synthetic strategy to prepare isoindolobenzazepine based lennoxamine alkaloid has been achieved in high ee% starting from 2-(benzo[d][1,3]dioxol-5-yl)ethanamine and 1-(chloromethyl)-2,3-dimethoxybenzene in 5 steps and with a 34% overall yield. The potentiality of this route involved the Bischler-Napieralsky cyclization that leads to tetracyclic indolinium skeleton, generation of chiral center through asymmetric hydrogen-transfer reaction employing l-proline-tetrazole as chiral ligand with Ru/Ir/Rh, and anodic oxidation as the key steps in the synthesis.