Analogs of 6-monoacetyl morphine (6-MAM) are described. These include analogs derivatized at either the C-3 position, the C-6 position, or the nor position of the molecule. These analogs allow for elaboration with linkers terminated by a functional group such as an activated ester, the functional groups being useful for attaching the molecule to other entities such as proteins, polysaccharides, and reporter groups.