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A new N-bromo sulfonamide reagent, namely N,2-dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide, was synthesized and used as a new and highly efficient catalyst for the preparation of 9-aryl-1,8-dioxo-octahydroxanthene derivatives by the condensation reaction of dimedone (5,5-dimethylcyclohexane-1,3-dione) and var...
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A new, simple, highly efficient method for the synthesis of different types of carbonyl chalcones through a regioselective condensation reaction of appropriate 5-acetyl-2-hydroxybenzaldehyde with various substituted acetophenones and 4-hydroxyisothalaldehyde with various substituted aldehydes using BF3–Et2O as a reagent is described.
Citations
In this paper, Na2Ca(HPO4)2 was used for the first time as a heterogeneous catalyst for efficient and green synthesis of 1,8-dioxo-octahydroxanthenes and biscoumarin derivatives. Under optimal conditions, the products were obtained with excellent yields in a short reaction time. This developed procedure has shown several advantages: avoiding toxic solvents, catalyst, simple handling, mild conditions, easy recovery, and catalyst reuse.
Na2Ca(HPO4)2 as a heterogeneous catalyst guarantees an environmentally friendly process; it can be considered an alternative to the other previously reported synthesis methods.
The 6-membered aza-heterocycles, 1,2,4-oxadiazines and 1,2,4-thiadiazines, are valuable scaffolds due to the vast spectrum of medicinal properties they possess. These scaffolds exist in several drugs or drug-leads such as MK-8428, mS-11, BPDZ44, and IDRA21. These can be classified as 2H-, 4H- or 6H-isomers depending upon the position of double bonds in the ring. The sulfur in thiadiazines exists in different oxidation states, namely, SII, SIV and SVI, of which SVI (1,2,4-benzothiadiazine-1,1-dioxide) is the most common oxidation state. This article discusses various methods such as cycloaddition, rearrangement and CH functionalization for the synthesis of 1,2,4-oxadiazines and 1,2,4-thiadiazines and their biological properties.
This chapter discusses the reactions of aldehydes and ketones and their derivatives. Several papers deal with the conversion of aldehydes to carboxylic acids, or oxidation to the acid level, such as anhydride or nitrile formation. Direct Mannich‐type reactions generating both alpha‐ and beta‐amino esters from a range of carbonyl compounds and aldimines have been described. Second‐order Moller‐Plesset perturbation theory has been employed to investigate their reactivity, with pericyclic reactions giving rise to five‐membered cyclic carbene intermediates, leading‐through subsequent hydrogen transfers‐to pyrazoles and imidazoles. Several asymmetric transfer hydrogenations were carried out on ketones in formic acid/triethylamine, using ruthenium catalysts. A review examines the current understanding of enantioselective reduction of prochiral aromatic ketones by Noyori and Nayari‐Ikariya bifunctional catalysts, two of the bestbehaved catalytic systems: they deliver up to 99.9% ee with very low catalyst loading of ca. 10‐5 mol%.
A heterogeneous solid acid catalyst has been prepared by covalent grafting of chlorosulphonic acid on the surface of sawdust (SD-OSO3H). The structure of the prepared catalyst was assessed by FT-IR, solid state CP/MAS ¹³C-NMR spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray. The catalytic performance of the solid acid catalyst has been evaluated in the synthesis of 1,8-dioxo-octahydroxanthenes and 1,8-dioxo-decahydroacridines. High conversion, shorter reaction time, cleaner reaction profile, environmentally benign solvent, simple experimental and work-up procedure, and reusability of catalyst are the striking features of our synthetic route.
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