Synthetic approaches to a carboranyl thiouracil.

Thiouracil is selectively incorporated into melanotic murine melanomas during melanin synthesis. This selectivity makes thiouracil a likely vehicle for boron in the diagnosis and therapy of melanoma. Several synthetic routes to thiouracils bearing an alkyl decacarboranyl group attached to various positions on the ring have been investigated. The successful syntheses of three new alkynyl thiouracils and the conversion of one of them into a carboranyl thiouracil are described.