A cross-coupling reaction at the carbon vertex of a monocarba-closo-dodecaborate has been developed to allow introduction of various aryl groups and other sp(2)/sp-hybridized carbon centers. A copper(I) complex facilitated the coupling process with a wide range of electrophiles at room temperature. The reaction was successfully used to prepare a series of C-arylated caborane anion derivatives, some of which showed potent androgen-receptor binding activity and excellent mesogenic properties.