Synthesis of Zwitter-Ionic Conjugate of Nido-Carborane with Cholesterol

9-HC≡CCH(2)Me(2)N-nido-7,8-C(2)B(9)H(11), a previously described carboranyl terminal alkyne, was used for the copper(I)-catalyzed azide-alkyne cycloaddition with azido-3β-cholesterol to form a novel zwitter-ionic conjugate of nido-carborane with cholesterol, bearing a 1,2,3-triazol fragment. The conjugate of nido-carborane with cholesterol, containing a charge-compensated group in the linker, can be used as a precursor for the preparation of liposomes for BNCT (Boron Neutron Capture Therapy). The solid-state molecular structure of a nido-carborane derivative with the 9-Me(2)N(CH(2))(2)Me(2)N-nido-7,8-C(2)B(9)H(11) terminal dimethylamino group was determined by single-crystal X-ray diffraction.