Immunotherapeutic agents

A compound of the formula:

• in which:
• (a) X is —O— or —(CnH2n)— in which n has a value of 0, 1, 2, or 3, and R1 is alkyl of one to 10 carbon atoms, monocycloalkyl of up to 10 carbon atoms, polycycloalkyl of up to 10 carbon atoms, or benzocyclic alkyl of up to 10 carbon atoms, or
• (b) X is —CH═ and R1 is alkylidene of up to 10 carbon atoms, monocycloalkylidene of up to 10 carbon atoms, or bicycloalkylidene of up to 10 carbon atoms;
• R2 is hydrogen, nitro, cyano, trifluoromethyl, carbethoxy, carbomethoxy, carbopropoxy, acetyl, carbamoyl, acetoxy, carboxy, hydroxy, amino, lower alkyl, lower alkylidenemethyl, lower alkoxy, or halo;
• R3 is pyrrolidine, imidazole or thiophene unsubstituted or substituted with 1 or more substituents each selected independently from the group consisting of nitro, cyano, halo, trifluoromethyl, carbethoxy, carbomethoxy, carbopropoxy, acetyl, carbamoyl, acetoxy, carboxy, hydroxy, amino, substituted amino, alkyl of 1 to 10 carbon atoms, alkoxy of 1 to 10 carbon atoms, or phenyl;
• each of R4 and R5 taken individually is hydrogen or R4 and R5 taken together are a carbon-carbon bond;
• Y is —COZ, —C≡N, or lower alkyl of 1 to 5 carbon atoms;
• Z is —OH, —NR6R6, —R7, or —OR7;
• R6 is hydrogen or lower alkyl;
• and R7 alkyl or benzyl.