DEVELOPMENT OF CARBORANE SYNTHONS - SYNTHESIS AND CHEMISTRY OF (AMINOALKYL)CARBORANES

A number of (aminoalkyl)-1,2-closo-dodocaboranes have been synthesized to provide carboranes with a functional group for covalent incorporation into structures of potential use in the treatment of cancer by boron neutron capture therapy (BNCT). (Phthalimidoalkyl)acetylenes reacted with decaborane to give the corresponding carboranes; removal of the phthalimido group under mild conditions using sodium borohydride in 2-propanol furnished the (aminoalkyl)carboranes which were isolated as their hydrochloride salts. An alternative approach involved the conversion of an (iodoalkyl)- or a ((tosyloxy)alkyl)carborane to the azido derivative which gave the amine on hydrogenation. An effective way of attaching a carborane moiety to thiouracil, which is selectively taken up in melanoma cells, is illustrated by the acylation of two of these amines with thiouracil-5-carboxylic acid.