RESUMO
This study demonstrates the successful formation of a radical anion intermediate in a moist atmosphere, facilitating chemical reactions by activating aerial dioxygen through a single electron transfer (SET) mechanism. Derived from deprotonating quinoxaline-2(1H)-one with KOtBu, it shows potential in oxygenation chemistry. Validation comes from radical scavenging and EPR experiments.
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A visible-light-mediated sustainable approach for metal-free oxygenation of quinoxalin-2(1H)-one by employing Mes-Acr-MeClO4 as a photocatalyst without using any additive or cocatalyst is reported here. O2 served as the eco-friendly and green oxidant source for this conversion. In addition, the protocol exhibited high regioselectivity and tolerance toward a broad spectrum of functional groups to furnish quinoxaline-2,3-diones in good to excellent yields.
RESUMO
The enlarged landscape of catalysis lies in the heart of chemistry. As the journey has set a milestone in organic synthesis, its darker side has not entered into the limelight. Studies disclose that the reported reactions by using catalysts were also attainable in the absence of catalysts in many cases. This article presents a literature collection that includes the significance of control experiments in hydrofunctionalization reactions. Systematic analysis reveals that the catalysts are ambiguous and might be unessential in chemical reactions enlisted here.
Assuntos
CatáliseRESUMO
In a chlorinative cyclization, Mes-Acr-MeClO4 acted as a visible-light photocatalyst to obtain 3-chlorocoumarins from aryl alkynoates and N-chlorosuccinimide (NCS). The radical initiated reaction proceeded in a cascading manner via Cl- addition to alkynoates. Next, 5-exo-trig spirocyclization and subsequent 1,2-ester migration led to the formation of C-C and C-Cl bonds.
RESUMO
We report a one-pot metal-free synthesis of 3-nitro-coumarins from aryl alkynoates using TBN (tert-butyl nitrite) as the sole reagent. The radical triggered cyclization and nitration of the aryl alkynoates proceeded in a cascaded manner via nitro radical addition to alkynoates, then 5-exo-trig spirocyclization and ester migration.
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Aluminum toxicity in biological systems is a well-known issue yet remains as a prevalent and unsolvable problem due to the lack of proper molecular tools that can detect free aluminum(iii) or Al(iii) ions in vivo. Herein, we report a water-soluble photo-induced electron transfer (PET)-based turn-ON/OFF fluorometric chemosensor for the dual detection of Al(iii) and fluoride ions in aqueous media with a nanomolar (â¼1.7 × 10-9 M) and picomolar (â¼2 × 10-12 M, lowest ever detection so far) detection limit, respectively. Fluoride ions in sea water could be detected as well as the recognition of non-contamination in drinking water. In addition, using live-cell microscopy, Al(iii) ions were detected in live biological samples in vivo to aid establishing the aluminum-toxicity effect.
Assuntos
Alumínio/toxicidade , Corantes Fluorescentes/química , Fluoretos/análise , Alumínio/química , Animais , Sobrevivência Celular/efeitos dos fármacos , Íons/análise , Camundongos , Estrutura Molecular , Imagem Óptica , Células RAW 264.7RESUMO
Herein, a highly exothermic primary amine-polyvalent iodine reaction has been used successfully for selective functionalization of acidic C(sp3)-H groups for a dehydrogenative C-H imination reaction by 4H elimination. Overall, C(sp3)-H imination at 1,5 distances was readily done via organocatalysis using PhI (10 mol%)-mCPBA under ambient conditions.