Synthesis of Functional Derivatives of 7,8-Dicarba-nido-undecaborate Anion by Ring-Opening of Its Cyclic Oxonium Derivatives

Abstract

A new approach to synthesis of functional derivatives of 7,8-dicarba-nido-undecaborate anion based on ring-opening of its cyclic oxonium derivatives [10-(CH 2 ) 4 O-7,8-C 2 B 9 H 11 ] and [10-O(CH 2 CH 2 ) 2 O-7,8-C 2 B 9 H 11 ] with various nucleophiles was developed. Both cyclic oxonium derivatives can be obtained as single isomers by reaction of the parent anion [7,8-C 2 B 9 H 12 ] -with mercury(II) chloride in the corresponding solvents. Mechanism of formation of the cyclic oxonium derivatives of 7,8-dicarba-nido-undecaborate anion was proposed. A series of 7,8-dicarba-nido-undecaborate derivatives with terminal carboxylic and azide functions were prepared by the ring-opening reactions of the cyclic oxonium derivatives with substituted phenolate and azide ions, respectively.

“Chemical Ligation”: A Versatile Method for Nucleoside Modification with Boron Clusters

“…[19] An analogous approach, but using ethyl alcohol instead of dimethylformamide as a reaction medium, was published recently by other authors. [20] Table 1 summarizes the characteristics of compounds 2-6, 7, and 8.…”

“….55 (s, B8'), 0.35 (s, B10'), À2.51 (s, B10 overlap), À4.48 (s, B4',7'), À7.26 (s, B9',12'), À8.12 (s, B9,12), À17.34 (s, B5',11'), À20.39 (s, B5,11), À22.10 (s, B6' overlap), À28.62 ppm (s, B6); MS (FAB, Gly, -ve,): m/z (%): calcd for C 20 …”

Focus on Chemistry of the 10-Dioxane-nido-7,8-dicarba-undecahydrido Undecaborate Zwitterion; Exceptionally Easy Abstraction of Hydrogen Bridge and Double-Action Pathways Observed in Ring Cleavage Reactions with OH− as Nucleophile

“…Eleven vertex 7,8-Dicarba-nido-dodecahydroundecaborate(1−) ion [1] belongs to the most studied boron cluster anions due to its easy availability from ortho-carborane [2], open pentagonal C 2 B 3 plane with three stereochemically distinctive sites for substitution and an extra hydrogen atom sitting on it [3,4]. It is well recognized that the coupling of the [nido-7,8-C 2 B 9 H 12 ] − ion with tetrahydrofuran and dioxane promoted by various metal halides, such as FeCl 3 [5] or HgCl 2 [6,7], yields the neutral zwitterionic compounds [10-(CH 2 ) 4 O)-nido-7,8-C 2 B 9 H 11 ] or [10-(O-(CH 2 -CH 2 ) 2 O)-nido-7,8-C 2 B 9 H 11 ] (1). More recently, we reported that the dioxane derivative 1 can be produced in high yield by reaction of the neutral carborane nido-C 2 B 9 H 13 with dioxane used as solvent [8].…”

“…In this regard, the ring cleavage methodology brings a level of high versatility to a broad scope of applications. Furthermore, the resulting substituents are located on the cage in a symmetrically located position and hence the products are free from stereochemical complications such as the presence of diastereoisomeric pairs or chirality [7]. The compound, and its derivatives arising from ring cleavage, can potentially serve as new charge-compensated [41,42] or common type of ligands in the synthesis of metallacarboranes.…”

“…With regards to ring cleavage of the zwitterion 1 using nitrogen nucleophiles, only reactions with the azide ion [7] and butyl amine have been reported, the later within the synthesis of model inhibitors of HIV-Protease that bear two dicarbollide ions units interconnected with long aliphatic chains to a central n-alkylammonium group [8,36]. Compounds of this type are sometimes referred to as "dumbbells" [43].…”