Discovery of fluorescent 3-heteroarylcoumarin derivatives as novel inhibitors of anaplastic lymphoma kinase

Coumarin-based ALK inhibitors were identified as a new template for the development of novel fluorescent ALK inhibitors, which can be tracked using microscopy techniques.

Palladium-catalyzed oxidative C–H/C–H cross-coupling of imidazopyridines with azoles

A palladium-catalyzed oxidative C–H/C–H cross-coupling of imidazopyridines with azoles using air as the oxidant has been developed.

Mutation at G103 of MtbFtsZ Altered their Sensitivity to Coumarins

Coumarins are natural polyphenol lactones comprising of fused rings of benzene and α-pyrone. The current study demonstrates the inhibitory effect of coumarins with various substitutions on Mycobacterium smegmatis mc² 155. We also demonstrate the effect of pomegranate (Punica granatum) extract containing ellagic acid, on M. smegmatis as well as their affect on MtbFtsZ (FtsZ from Mycobacterium tuberculosis). The ellagic acid extracts from pomegranate peels inhibit mycobacteria with a MIC of 25 μM and 0.3 to 3.5 mg/mL, respectively, but failed to inhibit the polymerization of MtbFtsZ. However, the coumarins were shown to inhibit the polymerization and GTPase activity of the protein as well as have an inhibitory affect on M. smegmatis mc² 155. Docking of the most active coumarin (7-Dimethyl-4-methyl coumarin with MIC of 38.7 μM) to the GTP binding site suggests that it interacted with the G103 residue. Based on the docking results two mutants of varying activity (G103S and G103A) were constructed to elucidate the interaction of MtbFtsZ and coumarins. Mutation of G103 with Serine (a bulky group) results in an inactive mutant and substitution with alanine produces a variant that retains most of the activity of the wild type. There is a disruption of the protofilament formation of the MtbFtsZ upon interaction with coumarins as demonstrated by TEM. The coumarins increase the length of Mycobacteria five times and MtbFtsZ localization is disturbed. The mutant proteins altered the GTPase and polymerization activity of coumarins as compared to wild type protein. The results here support that coumarins inhibit proliferation of Mycobacteria by targeting the assembly of MtbFtsZ and provide the possible binding site of coumarins on MtbFtsZ. This study may aid in the design of natural products as anti-mycobacterial agents. The currently reported GTP analogs for FtsZ are toxic to the human cell lines; natural coumarins targeting the GTP binding site of MtbFtsZ may hold promise as an important drug lead for tuberculosis treatment.

Metal-free phosphonation of benzoxazoles and benzothiazoles under oxidative conditions

A metal-free C-2 phosphonation of benzoxazoles and benzothiazoles with trialkyl phosphites was described.

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity.

Photophysics of Derivatives of 3-Hydroxybenzo[c]coumarin

The photophysical studies of two phenols, derivatives of 3-hydroxybenzo[c]coumarin, were performed in n-nonane matrix at 5 K. Unstructured fluorescence spectrum of the derivative bearing a salicylaldehyde moiety, whose onset is shifted by ca. 3000 cm(-1) to lower energy in respect to that of absorption, and short decay time of this emission (0.75 ns) suggested the occurrence of excited-state intramolecular proton transfer (ESIPT). The experimental results were interpreted with the aid of quantum chemistry calculations performed with the DFT and TDDFT/B3LYP/6-31++G(d,p) methods.

A one-pot domino C–H, C–C activation in coumarins: a fast track to 2,3-diaryl benzo[b]furans

An approach to synthesize 2,3-diaryl benzo[b]furans using coumarins and aryl bromides is developed.

Regioselective palladium(ii)-catalyzed aerobic oxidative Heck-type C3 alkenylation of sulfocoumarins

An efficient method for the direct C–H olefination of sulfocoumarins with a wide range of alkenes is developed. Moreover, O₂ was successfully utilized as the sole oxidant for the oxidative Heck reaction. This approach enables the rapid generation of various 3-alkenylated sulfocoumarins.

A general Pd/Cu-catalyzed C–H heteroarylation of 3-bromoquinolin-2(1H)-ones

The Pd(OAc)₂/CuI system effectively catalyzes the coupling of 3-bromoquinolin-2(1H)-ones with a series of azoles to give 3-(heteroaryl)quinolin-2(1H)-ones in good yields.

A copper-mediated cross-coupling approach for the synthesis of 3-heteroaryl quinolone and related analogues

An efficient and practical method for the direct cross-coupling between quinolones and a range of azoles was developed via copper-mediated C–H functionalization.

Tandem aldehyde-alkyne-amine coupling/cycloisomerization: A new synthesis of coumarins

Cu-catalyzed A(3) coupling of ethoxyacetylene, pyrrolidine and salicylaldehydes led to a concomitant cycloisomerization followed by hydrolysis of the resultant vinyl ether to afford coumarins in a cascade process. The reaction proceeded through exclusive 6-endo-dig cyclization and is compatible with halo and keto groups giving coumarins in good to moderate yields.