Immune system modulators

A compound of Formula I or a pharmaceutically acceptable salt thereof,

• wherein
• X is absent or is an optionally substituted alkyl, cycloalkyl, aryl, alkylaryl, or heterocycle;
• Q is H, (CH2)qNR1R2, NR1(CH2)pNRbRc, OR1, or SR1, in which q is 0 or 1 and p is 2-4;
• R1 and R2 are each independently hydrogen, alkyl, alkenyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, heterocycle, alkylheterocycle, or R1 and R2, when connected to N, together with the nitrogen atom to which they are bonded form a heterocycle, which may be optionally substituted by from one to four groups which may be the same or different selected from the group consisting of optionally substituted (C1-C4)alkyl, phenyl, benzyl, C(═O)R12, (CH2)pORa, and (CH2)pNRbRc, in which p is 2-4;
• R7 is NR3R4;
• R3 and R4 are each independently hydrogen, alkyl, cycloalkyl, alkenyl, or alkylaryl, or R3 and R4 together with the nitrogen atom to which they are bonded form a heterocycle;
• Y is oxygen, sulfur, or NR11, where R11 is hydrogen, alkyl, cycloalkyl, alkenyl, or aryl group;
• R12 is alkyl, aryl, or heterocycle;
• L is alkyl or alkenyl containing from 2 to 10 carbon atoms;
• R5 is hydrogen, halogen, cyano, ORa, SRa, S(═O)Ra, S(═O)2Ra, NRbRc, S(═O)2NRbRc, C(═O)ORa, C(═O)Ra, C(═O)NRbRc, OC(═O)Ra, OC(═O)NRbRc, NRbC(═O)ORa, NRbC(═O)Ra, or NRb(CH2)pNRbRc;
• R6 is halogen, cyano, aryl, SRa, S(═O)Ra, S(═O)2Ra, NRbRc, S(═O)2NRbRc, C(═O)ORa, C(═O)Ra, C(═O)NRbRc, OC(═O)Ra, OC(═O)NRbRc, NRbC(═O)ORa, NRbC(═O)Ra, alkaryl, alkylheterocyclic, or NRb(CH2)pNRbRc;
• each occurrence of Ra is independently hydrogen, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl;
• and
• each occurrence of Rb and Rc is independently hydrogen, alkyl, cycloalkyl, heterocycle, aryl, or said Rb and Rc together with the nitrogen atom to which they are bonded optionally form a heterocycle comprising 1-4 heteroatoms, wherein the heterocycle is optionally substituted by (C1-C4)alkyl;
• provided that when R5 and R6 are H or methyl, then Q is not H.