Controlled drug release from dendrimers

A dendrimer coupled to a multiplicity of substituents of the formula

• at least one or both R1 and R2 is independently CN;
• NO2;
• optionally substituted aryl;
• optionally substituted heteroaryl;
• optionally substituted alkenyl;
• optionally substituted alkynyl;
• COR3 or SOR3 or SO2R3 wherein
• R3 is H or optionally substituted alkyl;
• aryl or arylalkyl, each optionally substituted;
• heteroaryl or heteroarylalkyl, each optionally substituted;
• or
• OR or NR2 wherein each R is independently H or optionally substituted alkyl;
• SR4 wherein
• R4 is optionally substituted alkyl;
• aryl or arylalkyl, each optionally substituted;
• or
• heteroaryl or heteroarylalkyl, each optionally substituted;
• wherein R1 and R2 may be joined to form a 3-8 member ring;
• and
• wherein one and only one of R1 and R2 may be H or may be alkyl, arylalkyl or heteroarylalkyl, each optionally substituted;
• each R5 is independently H or is alkyl, alkenylalkyl, alkynylalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted;
• D is a residue of a drug or prodrug coupled through O, S, or N;
• Y is absent and X is O or S;
• or
• Y is NBCH2 and X is O;
• wherein B is alkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl, each optionally substituted;
• and
• wherein said coupling to the dendrimer is through any of R1, R2, R5 or B.