Some aspects of the chemical behavior of icosahedral carboranes

Abstract

Important features of the chemical behavior of icosahedral carboranes are considered. The ways of introducing functional groups at the carbon and boron atoms of carboranes by conventional methods of organic chemistry and methods applicable only to carboranes are discussed. The latter methods include transformations of dicarbadodecaborate (14) dianions. Examples of the enantiomer ic resolution of optically active carboranes, whose chirality is associated with the molecular asym metry, are given. The diversity of chemical transformations of carboranes is exemplified by in tramolecular nucleophilic rearrangements, cross coupling reactions, and the formation of chelate metallacycles.

ortho-Carbaborane derivatives of indomethacin as cyclooxygenase (COX)-2 selective inhibitors

“…Most characteristically is the electron-withdrawing effect which decreases in the order ortho - to para -carbaborane. 27,28 The aim of this study was therefore to synthesize all three cluster analogues of indomethacin and to determine whether carbaboranes can be used as surrogates for the chlorophenyl ring to induce COX-2 selectivity.…”

Dicarba‐closo‐dodecaboranes with One and Two Ethynyl Groups Bonded to Boron

“…[7,8] This includes the incorporation of functional groups at the carbon vertices that may be achieved by deprotonation and subsequent reaction with an electrophile, as well as the modification of the substituents at the boron vertices (e.g., by electrophilic halogenation or alkylation).…”

“…[7] The first report on cross-coupling reactions using iodinated dicarba-closo-dodecaboranes as starting materials was published in 1981, [15] and 9-Me 3 -SiCC-closo-1,2-C 2 B 10 H 11 and 9-Me 3 SiCC-closo-1,7-C 2 B 10 H 11 were obtained from the corresponding iodinated alized dicarba-closo-dodecaboranes were characterized by elemental analysis, mass spectrometry, as well as by multinuclear NMR, IR, and Raman spectroscopy. The assignment of the NMR spectroscopic chemical shifts and the IR and Raman bands is supported by theoretical values derived from density functional calculations.…”

Cesium and Tetrabutylammonium Salt of the Ethynyl‐closo‐dodecaborate Dianion

“…So far, no examples of cross‐coupling reactions of partially iodinated { closo ‐B 12 } clusters to result in derivatives with vinyl, allyl, or alkynyl groups that are bonded to the cluster boron atoms have been described except for a conference report by two of us9 to the best of our knowledge. In contrast, related Pd‐catalyzed Kumada‐type cross‐coupling reactions that yield dicarba‐ closo ‐dodecaboranes containing functional groups bonded to boron are well established10 and for the isoelectronic { closo ‐1‐CB 11 } cluster some similar reactions have been described, as well 11…”