Current Organic Chemistry - Volume 23, Issue 18, 2019

Amines are important and valuable intermediates in the pharmaceutical, plastic and agrochemical industry. Hence, there is an increasing interest in developing improved process for the synthesis of amines. The heterogeneous catalytic hydrogenation of nitriles is one of the most frequently applied methods for the synthesis of diverse amines, but the homogeneous catalysis has also received a growing attention from the catalysis community. This mini-review provides an overview of the recent achievements in the selective reduction of nitriles using both homogeneous and heterogeneous transition metal catalysts.

The field of heterocyclic chemistry has been revolutionized using transition metal catalysts in recent years. Various research groups have focused on the development of general protocols to achieve better functional group compatibilities and greater levels of molecular complexity under mild reaction conditions, using easily available starting substrates. The methodologies used earlier for their synthesis were less approachable to organic chemists because of their high cost, highly specified instrumentation and inconvenient methods. For both stereoselective and regioselective synthesis of five-membered nitrogen- containing heterocycles, cyclic reactions that are Ru-catalyzed have known to be very efficient. These methods have many advantages as compared to alternative pathways involved in the synthesis of heterocyclic compounds. In this review article, we concentrated on the synthesis of nitrogen-containing five-membered heterocycles in the presence of a ruthenium catalyst. This review mostly covers the literature published during the period from 1977-2019.

Arylglyoxals are important synthons that have been used in the construction of a diverse spectrum of compounds. The use of multicomponent approaches in organic synthesis due to its environmentally friendly nature is a step forward towards sustainability. This review will offer the reader insightful perspectives on the use of arylglyoxals for the synthesis of various heterocyclic compounds like pyrroles, pyrazoles, furans, imidazoles, indoles, oxazoles, pyridines, quinazolines, pyrans, etc using multicomponent approach.

A new method for the preparation of three new curcumin analogues is described by the connection of pentadienones to carbohydrate units. From L-Rhamnose and D-Galactose, several functionalization reactions were performed to obtain the desired sugar units. The sugars 8, 18 and 19, after obtained, were used as starting material for the association with curcumin-derived pentadienones, thus giving rise to three new chalcones 9 by O-glycosylation, 22 and 23 C-glycosylation. The new compounds were characterized by NMR and mass spectroscopy. The compounds obtained have high potential to exhibit antitumor activity.

In this study, the synthesis and evaluation of norfloxacin analogues of dimethyl citrate conjugates were described and their antibacterial and anticancer activities were assessed. The cognate 7-substituted norfloxacin citrate conjugates are active against various strains of bacteria, including MRSA (methicillin-resistant Staphylococcus aureus) with higher activity than ciprofloxacin. Screening results indicated that compound 10 possessed good antibacterial activity against several microorganisms, with MIC values in the range of 0.16-0.35 mg/mL and MBCs in the range of 0.55-0.84 mg/mL. Experiments indicated that 9 demonstrated the most significant activity towards the HCT-15 cell line with IC50 value 8.2 ± 0.139 and against the HT-29 cell line with IC50 8.9 ± 0.122. The title compounds were also evaluated for determining the molecular and pharmacokinetic properties and drug-likeness model scores by using the Molinspiration-2008 and MolSoft-2007 softwares. The region isomeric conjugates followed the Lipinski’s rule of five can be considered as potential antibacterial and anticancer bioavailable oral leads. Compounds 9 and 10 possessed maximum drug-likeness scores. The docking pose interactions of target compounds with the active site of enzyme PDB: 2ZCS of Staphylococcus aureus were estimated by using Autodock 4.2, to calculate the affinity, binding orientation of the ligand with the target protein and to explore the finest conformations. The target compounds, 7, 8, 9, 10, with protein, were loaded separately into Auto dock tools (ADT) and evaluated. The citrate conjugates, 8, 9, showed better docking scores with amino acids Lys17, Ser21, Val268, Lys273 and Arg171, Arg265, Val268, Val273 with the binding energy -5.70, -5.57 kcal/mol and dissociation constant 66.62, 82.13 μM respectively.