The synthesis of a new ortho-carborane derivative, tetracarboranylketone 4, is reported here. Ketone 4 was prepared from a tetraalkynylated ketone by the addition of decaborane. The keto group was then easily modified to yield the glycosides 17alpha and 18beta, which contain glucose or galactose, respectively, and the nucleotide 13b. In addition to ketone 4, which is acyclic, cyclic ketone 8 was also synthesised. X-ray diffraction analysis of compound 4 indicated the presence of two toluene guest molecules per molecule of the host compound. Furthermore, compound 4 displays a rather low cytotoxicity. These novel products can be used as building blocks to create a new class of biomolecules containing high-density carborane clusters. Such molecules may constitute powerful tools for applications like Boron Neutron Capture Therapy or Energy-Filtering Transmission Electron Microscopy.