A mild and eco-friendly visible-light-induced synthesis of 2-(2-Hydrazinyl) thiazole from readily accessible thiosemicarbazide, carbonyl, and phenacyl bromide in the absence of a metal catalyst and/or any extrinsic photosensitizer is reported....

An efficient, one-pot three-component reaction in the synthesis of a wide range of 2,4-disubstituted hydrazinyl thiazole scaffolds in ethanol at room temperature has been developed by the reaction of carbonyl compounds, phenacyl bromides, and thiosemicarbazide, using graphene oxide (GO) as a catalyst. The present catalytic method has many significant advantages such as shorter reaction time, broad substrate scope, low catalyst loading, environmentally benign solvent media, easy handling, and operational simplicity at room temperature. The products are identified based on their various spectroscopic data. The GO catalyst has a high reusability rate and is simple to recover. A mechanistic study suggests that the reaction takes place via a thiosemicarbazone intermediate, which is isolated and confirmed in this study using spectroscopic techniques. Thereafter, a molecular docking study has been performed to evaluate the binding affinity of hydrazinyl thiazole derivative as a possible inhibitor on the protein active site of human α-amylase and glucosamine 6-phosphate synthase[a] A

A facile and eco‐friendly sustainable synthesis of functionalized quinoxaline derivatives from 1,2‐diaminobenzenes and 2‐bromoacetophenones via a one‐pot two‐component reaction using choline chloride (ChCl): glycerol as a bio‐renewable DES has been developed. In this protocol, nucleophilic 1,2‐diaminobenzenes are mixed with phenacyl bromides or 3‐(bromoacetyl) coumarin to produce quinoxaline derivatives in a high yield (up to 96 %), with a clean reaction profile without the use of a solvent or catalyst at ambient temperature (80 °C). The presence of DES is proven to be essential for assuring efficient transformation, as the product yield was extremely low with a slow reaction profile in the absence of this media. The DES media could be recycled and reused up to five times without losing its efficiency or affecting the chemical yield of the reaction. In the showcase study, the reaction was also scaled up to the gram scale (10 mmol scale), revealing the synthetic potential of the current approach. A DFT calculation has been also performed to probe the mechanism and reversal of the regioselectivity in the products formation.

Hydrazinyl thiazole is frequently encountered in natural as well as in synthetic compounds. It is also an important pharmacophore and has some other useful applications. In this review article, we have compiled different green synthetic procedures for the synthesis of hydrazinyl thiazole derivatives. Also, the critical analysis of different synthetic schemes will help to understand the lacks in developed procedures and to develop new methodologies regarding its synthesis, specially using heterogeneous organocatalyst and photocatalyst.

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