| abstract |
Diphosphonic acids of formula (I) are described, in which R1 and R2 represent hydrogen or C1-C4 alkyl; A represents hydrogen, halogen, hydroxy or C1-C12 alkyl; B represents a covalent bond, a C1-C8 alkyl chain, an alkyl chain containing a heteroatom (O, S or N-CH3), a cycloalkyl chain, an alkyl chain substituted by cyclohexyl or cyclopentyl groups or a chain aralcoyl; R3 represents hydrogen, C1-C9 alkyl, C3-C6 cycloalkyl, benzyl, phenyl or p-methoxybenzyl; R4 and R5 with the alpha group are the residue of an amino acid D or L; q is 0 or 1. These compounds are useful as anti-tumor agents. |