Metal-free synthesis of dihydrofuran derivatives as anti-vicinal amino alcohol isosteres.

Dihydrofuran cores are commonly incorporated into synthetically and pharmacologically significant scaffolds in natural product and drug discovery chemistry. Herein, we report a concise and practical strategy to construct spiro-dihydrofuran and amino dihydrofuran scaffolds as anti-vicinal amino alcohol isosteres. Hypervalent iodine (PhI(OAc)(NTs2))-mediated C-H activation of alkynes resulted in two-bond formations with one pi bond cleavage: (i) C(sp2)-N(sp3) and O(sp3)-C(sp2); (ii) C(sp2)-N(sp3) and C(sp3)-C(sp2). The metal-free 5-endo-dig oxidative cyclization provided versatile amino 2,3- and 2,5-dihydrofurans bearing the C5 quaternary carbon. The non-toxicity of all synthesised dihydrofurans was verified via in vitro cell viability assay.

Modular assembly of furotropones and benzofurotropones, and study of their physicochemical properties.

A rapid and straightforward synthesis of a novel series of furo[2,3-d]tropones (or cyclohepta[b]furan-6-ones) has been developed starting from readily and commercially available materials. Directed α-lithiation of furan-3-carboxaldehydes and subsequent reaction with a variety of aldehydes efficiently provide, in one step, access to 3-formyl-2-furylcarbinols, which are otherwise only accessible with difficulty. The 3-formyl-2-furylcarbinols are further elaborated in two steps to the synthesis of furo[2,3-d]tropones in good yields via sequential bismuth(III)chloride-catalyzed furfurylation and an unusual base promoted cyclization strategy. Thus, diverse polysubstituted furotropones and benzofurotropones can be rapidly assembled. This methodology thereby offers a potential approach for the synthesis of several bioactive natural products containing cyclohepta[b]furan core and also for the buildup of complex molecular architectures through higher order cycloaddition reactions of tropones. Further, the new chromophores have been found to possess promising fluorescence properties. Selective fluorogenic sensing behavior of furotropones toward Fe(3+) ions has also been elucidated.

Spectral characteristics of the flavones and anthocyanins present in passionflower (Passiflora incarnata).

Rich in antioxidants with a variety of flavones and anthocyanins, passionflower/fruit has been extensively used in food, beverage, medicinal, and natural dyes industries. The individual components present in passionflower are identified by extracting them in methanol, partitioning them between ethyl acetate and aqueous layers, and recording their ESI mass spectrometric data. The steady-state absorption and fluorescence spectra of the extract in methanol and dimethyl sulfoxide are recorded and the lifetime of the fluorescing species is reported. The pH dependence of the absorption spectrum confirms the presence of the anthocyanins.

Tunable fluorescent probes for detecting aldehydes in living systems.

Aldehydes, pervasive in various environments, pose health risks at elevated levels due to their collective toxic effects via shared mechanisms. Monitoring total aldehyde content in living systems is crucial due to their cumulative impact. Current methods for detecting cellular aldehydes are limited to UV and visible ranges, restricting their analysis in living systems. This study introduces an innovative reaction-based trigger that leverages the exceptional selectivity of 2-aminothiophenol for aldehydes, leading to the production of dihydrobenzothiazole and activating a fluorescence response. Using this trigger, we developed a series of fluorescent probes for aldehydes by altering the fluorophore allowing for excitation and emission wavelengths across the visible to near-infrared spectral regions without compromising the reactivity of the bioorthogonal moiety. These probes exhibit remarkable aldehyde chemoselectivity, rapid kinetics, and high quantum yields, enabling the detection of diverse aldehyde types, both exogenous and endogenous, within complex biological contexts. Notably, we employed the most red-shifted near-infrared probe from this series to detect aldehydes in living systems, including biliary organoids and mouse organs. These probes provide valuable tools for exploring the multifaceted roles of aldehydes in biological functions and diseases within living systems, laying the groundwork for further investigations.

Catalytic Enantioselective Synthesis of Axially Chiral Diarylmethylidene Indanones.

We describe the first atropselective Suzuki-Miyaura cross-coupling of ß-keto enol triflates to access axially chiral (Z)-diarylmethylidene indanones (DAIs). The chemical, physical, and biological properties of DAIs are unknown, despite their being structurally similar to arylidene indanones, primarily due to the lack of racemic or chiral methods. Through this work, we demonstrate a general and efficient protocol for the racemic as well as the atropselective synthesis of (Z)-DAIs. An unusual intramolecular Morita-Baylis-Hillman reaction is utilized for the Z-selective synthesis of ß-keto enol triflates.

Organocatalytic ß-Azidation of Enones Initiated by an Electron-Donor-Acceptor Complex.

An operationally straightforward organocatalytic ß-azidation of α,ß-unsaturated ketones is described. Reaction of the Zhdankin azidoiodane with enones in the presence of a catalytic amount of an amine provides ß-azido ketones via the formation of an electron-donor-acceptor complex. The application of this protocol is demonstrated through one-step elaborations leading to the synthesis of unprecedented classes of 1,2,3-triazoles.