Abstract: The invention provides a class of compounds and compositions thereof having the structure: ##STR1## wherein A is: ##STR2## The invention also concerns a method of selectively inducing terminal differentiation of neoplastic cells thereby inhibiting proliferation of such cells which comprises contacting the cells under suitable conditions with an amount of the compound to selectively induce terminal differentiation. It also provides a method of treating a patient having a tumor characterized by proliferatoin of neoplastic cells comprising administration of an amount of the compound effective to inhibit proliferation and suppress oncogenicity of neoplastic cells.