Synthesis and Characterization of a Multi Ring-Fused 2-Pyridone-Based Fluorescent Scaffold

A single pot organocatalytic diastereoselective synthesis of fluorescent ring fused 2-pyridone decalines via a domino Knoevenagel/Michael/hydro-lactamisation sequence

A highly efficient one-pot triple cascade approach is developed to synthesise fluorescent, fused, octahydro-2-pyridone decalines in good to excellent yields using l-proline/PhCOOH as an organocatalyst.

Synthesis of Densely Functionalized N-Alkenyl 2-Pyridones via Benzyne-Induced Ring Opening of Thiazolino-Fused 2-Pyridones

We report the synthesis of 6-arylthio-substituted-N-alkenyl 2-pyridones by ring opening of bicyclic thiazolino-2-pyridones with arynes. Varied functionalization was used to investigate scope and substituent influences on reactivity. Selected conditions favor thioether ring opening over [4 + 2] cycloaddition and an unusual aryne incorporating ring expansion. Deuterium labeling was used to clarify observed reactivity. Using the knowledge, we produced drug-like molecules with complex substitution patterns and show how thioether ring opening can be used on scaffolds with competing reactivities.

New 1,2-Dihydropyridine-Based Fluorophores and Their Applications as Fluorescent Probes

New 1,2-dihydropyridine (1,2-DHP)-based fluorophores 1a-1h were designed and synthesized by a one-pot four-component condensation reaction using dienaminodioate, aldehydes, and an in situ-generated hydrazone mediated by trifluoroacetic acid. The photophysical properties of 1,2-DHPs were studied in detail, and a few of them exhibited selective mitochondrial staining ability in HeLa cell lines (cervical cancer cells). A detailed photophysical investigation led to the design of 1,2-DHP 1h as an optimal fluorophore suitable for its potential application as a small molecule probe in the aqueous medium. Also, 1,2-DHP 1h exhibited sixfold enhanced emission intensity than its phosphorylated analogue 1h' in the long wavelength region (λ_em ≈ 600 nm), which makes 1,2-DHP 1h' meet the requirement as a bioprobe for protein tyrosine phosphatases, shown in L6 muscle cell lysate.

A one-pot, metal-free approach to bicyclic 2-pyridones

A practical one-pot process based on two-fold intramolecular cyclizations provides a more expedient entry into a variety of bicyclic 2-pyridones.

Synthesis of multi ring-fused imidazo [1,2- a]isoquinoline-based fluorescent scaffold as anti-Herpetic agent

BACKGROUND

Natural product-inspired synthesis is a key incorporation in modern diversity-oriented synthesis to yield biologically novel scaffold. Inspired by β-carboline fused system, we have designed molecules with multi ring fused scaffold by modifying the tricyclic pyrido[3,4- b]indole ring with imidazo[1,2- a]isoquinoline.

METHODS

A highly convergent approach with new C-N and C-C bond formation to synthesize multiring fused complex scaffold imidazo[1,2- a]isoquinolinies as fluorophores. N-nucleophile-induced ring transformation of 2 H-pyran-2-one followed by in situ cis-stilbene-type oxidative photocyclization yielded new C-C bond formation without additional oxidant. The cytotoxicity, effective concentrations, and the mode of action of the synthesized analogs were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT),, plaque reduction, time of addition, and reverse transcriptase Polymerase Chain Reaction (PCR).

RESULTS

Novel imidazo[1,2- a]isoquinoline analogs were prepared, and the results revealed that trans isomer of cyclopropyl analog (EC₅₀ 35 and 37.5 µg/ml) and trans isomer of citric acid salt of phenyl analog (EC₅₀ 38.2 and 39.8 µg/ml) possess significant anti-Herpes Simplex Virus (HSV) activity with selectivity index of >10. The kinetic study demonstrated that both the analogs inhibited HSV-1F and HSV-2G at 2-4 h postinfection. Finally, western blot and reverse transcriptase PCR assays revealed that both the analogs suppressed viral immediate early transcription.

CONCLUSION

Novel imidazo[1,2- a]isoquinoline analogs were synthesized from pyranone with appropriate amines. Two compounds showed better antiviral profile on HSV-infected Vero cells, compared to the standard drug acyclovir (ACV). Overall, we discovered a promising scaffold to develop a nonnucleoside lead targeting the viral immediate early transcription for the management of HSV infections.

Unusual light spectroscopic properties of a 2-pyridone-based multi-ring-fused fluorescent scaffold

UV-VIS absorption and fluorescence spectroscopic properties of six related polyaromatic 2-pyridones have been studied. Excitation of the lowest and rather weak and structure-less transition [ε (max) (430 nm) ≈ 3,000 mol(-1)dm(3)cm(-1)] gives rise to a broad fluorescence band in the visible region, for these compounds. These S (0) ↔ S (1) transitions are compatible with symmetrically forbidden transitions, promoted by intensity borrowing, as is revealed by fluorescence depolarisation data. With one exception, all compounds exhibit strong fluorescence, with quantum yields in glycerol varying between 40% and 70%. The corresponding fluorescence lifetimes range from 11 ns to 17 ns, while the radiative lifetimes are very similar (≈26 ns), for all compounds. Interestingly and rarely observed, the calculated radiative lifetimes for the weak absorption band are significantly longer, i.e. between 37 and 40 ns.