Carborane Compounds for Neutron Capture Therapy of Malignant Melanoma

Abstract

The possibility of using thiouracil as a vehicle for stable nuclei such as ¹⁰B for neutron capture therapy (NCT) of melanoma was first discussed by Fairchild and co-workers¹ in 1982. Since then a number of boron-containing thiouracils have been synthesized and investigated.²’³ Our research has been directed towards the design and synthesis of a number of o-carboranyl-thiouracils, the ten boron atoms of the carborane cage having a clear advantage for NCT. Our first step was the preparation, previously reported, of thiouracils bearing an alkyl group containing a triple bond for later elaboration to a carborane.⁴ The present paper describes the continuation of this work with the preparation of the carboranes of this series and its extension to the synthesis of a thiouracil in which a carboranylalkyl group is attached to the nitrogen in the 3-position.