A TfOH-promoted synthesis of fluorinated polyfused heterocycles via the cascade cyclization of azadienes and difluoroenoxysilanes has been developed, leading to the facile construction of and 5,6-dihydrobenzo[h]quinolines. This one-pot formal [4 + 2] approach involves 1,4-difluoroalkylation, desulfonylation, cyclization, and dehydrated and dehydrofluorinated aromatization and represents the first application of difluoroenoxysilane in cascade transformations. Furthermore, this methodology is highlighted by the synthesis of three fluoro analogues of bioactive molecules with potent topoisomerase inhibitory activities.

Alcohols can be efficiently converted into the useful thioethers by a transition metal- and base-free dehydrative S-alkylation reaction with thiols or disulfides by employing alkyl halides as the effective catalyst. This simple and efficient method is a green and practical way for the preparation of thioethers, as it tolerates a wide range of substrates such as aryl and alkyl thiols, as well as benzylic, allylic, secondary, tertiary, and even the less reactive aliphatic alcohols.

An electrochemical quercetin (QR) sensor is described that is based on the use of magnetic reduced graphene oxide (MrGO) incorporated into a molecularly imprinted polymer (MIP) on the surface of a screen-printed electrode (SPE). The MrGO consists of reduced graphene oxide (rGO), magnetite (FeO) and silver nanoparticles (Ag). The analyte (QR) is electrostatically adsorbed on the surface of the MrGO. Finally, the MIP was deposited via in-situ polymerization. The composite was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Vibrating sample magnetometry. The morphologies and electrochemical properties of different electrodes were characterized by Field emission scanning electron microscopy, Electrochemical impedance spectroscopy and differential pulse voltammetry. Under optimal conditions, the modified electrode has a linear response in the 20 nM to 250 μM QR concentration range. The limit of detection is 13 nM (at an S/N ratio of 3). The electrode is selective, stable, regenerable and reliable. It was applied to the determination of QR in spiked pharmaceutical samples and gave satisfactory results. Graphical abstract Schematic presentation of a method for sensing quercetin. It is based on the use of screen printed electrode modified with magnetized reduced graphene oxide and a molecularly imprinted polymer.

Dedicatedtot he memory of Professor Xian Huang for his contributions in organochalcogen chemistry.Supporting information for this article can be found under http://dx.Abstract: Am etal-and base-freet hree-component coupling of alcohols,h eteroarylh alides,a nd thiourea has been developedf or direct and selective synthesis of heteroaryl thioethers.T hism ethod can be easily scaled up to the gram scale and extended to dialkyl thioethers,h eteroaryls elenides,b enzothiazoles,a nd some antimycobacterially-active thioethers.M echanistic studies revealedt hat ab y-product-promoted in situ C-O activation of alcoholst o more reactive alkyl halides and slow releaseo ft he thiol and alkyl halide intermediates are the key to the high selectivity and success of the reaction.

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