Ntdo-Carboranes

In order to solve the problem of the significant toxicity of liposomes prepared from ntdo-carborane lipids 2 and 3, ctoo-dodecaborate has been focused on as an alternative hydrophilic function of boron lipids. BSH is known as a water-soluble divalent c/050-type anion cluster and significantly lowered toxicity (Haritz et al., 1994), and thus has been utilized for clinical treatment of BNCT. Nakamura and coworkers succeeded in the synthesis of double-tailed cZoso-dodecaborate lipids 4a-c and 5a-c, which have a B,2H S-moiety as a hydrophilic function with chirality similar to natural phospholipids, such as distearoylphosphatidylcholine (DSPC), in their lipophilic tails (Lee et al., 2007 Nakamura et al., 2007a). 

Removal of one of the boron atoms adjacent to both the carbon atoms of ortho-catborme by action of base results in the formation of anionic 7,8-dicarba-ntVft)-undecaborate (ntdo-carborane) [7,8-C2B9Hi2] . This approach is often used to increase the water solubility of carborane-containing biomolecules [10]. Recently, an efficient method of direct functionalization of the parent nido-carborane has been described [11]. 

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