| abstract |
The invention provides compounds of the formula <IMAGE> (I) or a pharmaceutically acceptable salt thereof, wherein [D] is the residue of a drug having a reactive functional group, said functional group being attached, directly or through a bridging group, via an oxygen-phosphorus bond to the phosphorus atom of the <IMAGE> moiety; R1 is C1-C8 alkyl, C6-C10 aryl or C7-C12 aralkyl; R2 is hydrogen, C1-C8 alkyl, C6-C10 aryl, C4-C9 heteroaryl, C3-C7 cycloalkyl, C3-C7 cycloheteroalkyl or C7-C12 aralkyl; and R3 is selected from the group consisting of C1-C8 alkyl; C2-C8 alkenyl having one or two double bonds; (C3-C7 cycloalkyl)-CrH2r- wherein r is zero, one, two or three, the cycloalkyl portion being unsubstituted or bearing 1 or 2 C1-C4 alkyl substituents on the ring portion; (C6-C10 aryloxy)C1-C8 alkyl; 2-, 3- or 4-pyridyl; and phenyl-CrH2r- wherein r is zero, one, two or three and phenyl is unsubstituted, or is substituted by 1 to 3 alkyl each having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, halo, trifluoromethyl, dialkylamino having 2 to 8 carbon atoms or alkanoylamino having 2 to 6 carbon atoms. The compounds are adapted for targeted drug delivery, especially to the brain. |