Organic amines are found to be abundant in natural living systems. They also constitute an inestimable family of building blocks available in drug design. Considering the man-made cluster [(1,2-C2B9H11)2-3,3'-Co(III)]- ion (1-) and its application as an emerging unconventional pharmacophore, the availability of the corresponding amines has been limited and those with amino groups attached directly to carbon atoms have remained unknown. This paper describes the synthesis of compounds containing one or two primary amino groups attached to the carbon atoms of the cobaltacarborane cage that are accessible via the reduction of newly synthesized azides or via the Curtius rearrangement of the corresponding acyl azide. This substitution represents the first members of the series of azides and primary amines with functional groups bound directly to the carbon atoms of the cage. As expected, the absence of the linker along with the presence of the bulky anionic polyhedral ion leads to a significant alteration of the chemical and physicochemical properties. On a broader series of amines of the ion 1- we have thus observed significant differences in the acidity of the amino groups, depending on whether these are attached to the carbon or boron atoms of the cage, or the C-substituted amines contain an aliphatic linker of variable length. The compounds are relevant for potential use as cobalt bis(dicarbollide) structural blocks in medicinal chemistry and material science. Our study includes single-crystal X-ray diffraction (XRD) structures of both amines and a discussion of their stereochemical and structural features.

• Publikační typ
• časopisecké články MeSH

The cobalt bis(dicarbollide)(1-) anion (1-), [(1,2-C2B9H11)2-3,3'-Co(III)](1-), plays an increasingly important role in material science and medicine due to its high chemical stability, 3D shape, aromaticity, diamagnetic character, ability to penetrate cells, and low cytotoxicity. A key factor enabling the incorporation of this ion into larger organic molecules, biomolecules, and materials, as well as its capacity for "tuning" interactions with therapeutic targets, is the availability of synthetic routes that enable easy modifications with a wide selection of functional groups. Regarding the modification of the dicarbollide cage, syntheses leading to substitutions on boron atoms are better established. These methods primarily involve ring cleavage of the ether rings in species containing an oxonium oxygen atom connected to the B(8) site. These pathways are accessible with a broad range of nucleophiles. In contrast, the chemistry on carbon vertices has remained less elaborated over the previous decades due to a lack of reliable methods that permit direct and straightforward cage modifications. In this review, we present a survey of methods based on metalation reactions on the acidic C-H vertices, followed by reactions with electrophiles, which have gained importance in only the last decade. These methods now represent the primary trends in the modifications of cage carbon atoms. We discuss the scope of currently available approaches, along with the stereochemistry of reactions, chirality of some products, available types of functional groups, and their applications in designing unconventional drugs. This content is complemented with a report of the progress in physicochemical and biological studies on the parent cobalt bis(dicarbollide) ion and also includes an overview of recent syntheses and emerging applications of boron-substituted compounds.

• Klíčová slova
• borane, carborane, cobalt bis(dicarbollide), dicarbollide, lithiation, metalation,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH