Radiobromination of<i>closo</i>-carboranes using palladium-catalyzed halogen exchange

Abstract

closo-Carborane derivatives are often proposed as boron carriers for use in boron neutron capture therapy (BNCT) of cancer. A positron emitting radiolabel on a boron atom in such carborane compounds might facilitate pharmacokinetic studies in patients. In this paper the four iodo-closo-carboranes, namely 3-iodo-ortho-carborane, 9-iodo-ortho-carborane, 9-iodo-meta-carborane and 2-iodo-para-carborane were chosen as model compounds in a study of [76Br]bromine labelling of carboranes using palladium-catalyzed halogen exchange. It was found that within a reaction time of 40 min, the four compounds were all radio-brominated in good to excellent yield, using Herrmann's catalyst (HC) in toluene. Copyright © 2005 John Wiley & Sons, Ltd.