A rapid metal-and additive-free room temperature method for C(sp 2 )-H thiocyanation of aminopyrazoles, aminoisoxazole, aminoisothiazole, amino uracils, and aliphatic enamines has been developed in an aqueous medium using hydrogen peroxide as a benign oxidant and ammonium thiocyanate as a thiocyanating agent. On the other hand, the reaction of hydrogen peroxide and ammonium thiocyanate followed by one-pot addition of NaOH provides the corresponding disulfides in the case of amino azoles, and pyrimidine-fused 2-amino thiazoles were observed in the case of aminouracils. The salient features of this method are the use of an eco-friendly oxidant, reaction tunability to access different products, wide substrate scope, and good to very good yields.

Herein, we report an efficient methodology for the synthesis of alkyl, benzyl, and phenyl selenoethers of aminopyrazoles and aminouracils by C­(sp2)–H functionalization in the presence of visible light and Rose Bengal as an organophotocatalyst. The reaction of amino pyrazole/iosothiazole/isoxazole or amino uracils with 0.5 equivalent of diphenyl/dibenzyl/diethyl diselenides in the presence of visible light in acetonitrile medium and a catalytic amount of Rose Bengal provided the corresponding phenyl, benzyl, or ethyl selenoethers in good to very good yields. We have also utilized some of the selenylated aminopyrazoles for the preparation of pyrazole-fused dihydropyrimidines tethered with arylselenoethers by a catalyst-free one-pot three-component reaction. The notable features of this methodology are metal-free reaction conditions, good to very good yields, use of an organic photocatalyst, and wide substrate scope; it is also applicable to gram-scale synthesis and provides selenoethers of medicinally important heterocycles such amio-pyrazole, isoxazole, isothiazole, and uracils.

Herein we report iodine-mediated novel three-component reactions for the synthesis of naphthoquinone-fused pyrroles linked with a barbituric acid moiety.

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Cs2CO3 in dimethylformamide (DMF) is a perfect combination for the rapid room-temperature synthesis of 3-amino-2-aroyl benzofuran derivatives from the reaction of 2-hydroxybenzonitriles and 2-bromoacetophenones in good to excellent yields. Using this one-pot C–C and C–O bond-forming strategy, we prepared a series of 3-amino-2-aroyl benzofuran derivatives within a very short time (10–20 min). This method was also found suitable for gram-scale synthesis. Benzofurans (3) obtained by this Cs2CO3-mediated methodology were then further explored for the development of a tunable base- and ligand-free copper-catalyzed N-arylation methodology using arylboronic acids for the easy access of either mono- or bi-N-aryl derivatives of aminobenzofurans at ambient temperature. The reaction of 3 with malononitrile in DMF medium under microwave heating conditions provided highly fluorescent conjugated alkenes and novel pyridine-fused benzofurans.