Novel oxathiazinones as gastrin ligands : Unexpected preducts from the schotten-baumann reaction of arylsulphonyl chlorides with derivatives of aspartic acid

Carboxylic Acid Bioisosteres in Medicinal Chemistry: Synthesis and Properties

Lead optimization represents the tedious process of fine-tuning lead compounds from biologically active hits to suitable drug candidates for clinical trials. By chemically modifying a hit structure, an improved compound can be obtained in terms of activity, selectivity, and pharmacokinetic ADME (absorption, distribution, metabolism, and excretion) properties. The carboxylic acid moiety is known to be a crucial functionality in many pharmaceutically active compounds. Despite its common use as a key functionality in drugs, its presence in a lead molecule is often associated with poor pharmacokinetic properties and toxicity. In this literature overview, we discuss how the shortcomings of a carboxylic acid can be circumvented by replacing this functionality with bioisosteres. In this way, the positive aspects of this moiety, such as its activity, for example, by virtue of its capacity to form hydrogen bonds, can be maintained or even improved. To that end, we provide an overview of the most promising carboxylic acid bioisosteres and discuss a selection of synthetic routes towards the main functionalities.

Selective Extraction of Platinum(IV) from the Simulated Secondary Resources Using Simple Secondary Amide and Urea Extractants

The recycling of rare metals such as platinum (Pt) from secondary resources, such as waste electronic and electrical equipment and automotive catalysts, is an urgent global issue. In this study, simple secondary amides and urea, N-(2-ethylhexyl)acetamide, N-(2-ethylhexyl)octanamide, and 1-butyl-3-(2-ethylhexyl)urea, which selectively extract Pt(IV) from a simulated effluent containing numerous metal ions, such as in an actual hydrometallurgical process, were synthesized and achieved efficient Pt(IV) stripping using only water. Comparison of Pt(IV) extraction behavior with a tertiary amide without N–H moieties suggests that the secondary amides and urea extractants effectively use hydrogen bonding to the hexachloroplatinate anion by N–H moieties. Examining the conditions for the third phase formation revealed that the secondary amide extractant with the longest alkyl chain can be used in the extraction process for a long time without forming any third phase, despite its lower Pt(IV) extraction capacity. The practical trial with simple compounds developed in this study should contribute to the development of Pt separation and purification processes.

A Facile and Eco-Friendly Method for the Synthesis of Sulfonamide and Sulfonate Carboxylic Acid Derivatives—X-ray Structure, Hirshfeld Analysis and Spectroscopic Characterizations

The search for a simple and efficient method for the synthesis of sulfonamide and sulfonate derivatives under mild and eco-friendly conditions is of continuing interest. Sulfonyl chlorides are still the best choice as starting materials for the preparation of target products. Here, we report a simple, efficient and eco-friendly method for the synthesis of sulfonamide and sulfonate carboxylic acid derivatives under green conditions using water and sodium carbonate as HCl scavengers to produce the products with high yields and purities. Two derivatives, 4-(tosyloxy)benzoic acid (5a) and 4-((4-methylphenyl)sulfonamido)benzoic acid (5b), were reacted with 2-morpholinoethan-1-amine under green conditions, where OxymaPure/diisopropylcarbodiimide (DIC) was used as a coupling reagent and 2-MeTHF as a solvent to give the target product with high yield and purity. nuclear magnetic resonance (NMR) and elemental analysis confirmed the structures of all obtained products. X-ray crystallography confirmed the structures of products 4b, 4c and 7a. The molecular packing of the three compounds (4b, 4c and 7a) was analyzed using Hirshfeld topology analysis. Mainly, H…O hydrogen bonding interactions dominated the packing. These methods of preparation and coupling merit further attention for the development of new derivatives that might have significant biological applications.