Synthesis of conjugates of closo-dodecaborate dianion with cholesterol using a “click” reaction

The nucleophilic ring-opening reaction of tetrahydropyran derivative of the closo-dode-caborate dianion with sodium azide in the presence of tetrabutylammonium bromide led to the novel azido-derivatives of[B12H12]2−. A Cu-catalyzed 1,3-dipolar [3+2] cycloaddition reaction of the closo-dodecaborate dianion azido-derivatives with alkynyl-cholesterol led to 1,4-disubstituted 1,2,3-triazoles with the closo-dodecaborate fragment at position 1. The resulting conjugates are potentially suitable for the development of liposomal drugs to selectively deliver boron into a tumor cell for boron neutron capture therapy of cancer.