This invention features pyrimidine compounds of formula (I): R1 is formula (II), aryl, or heteroaryl; each of R2 and R4, independently, is Rc, halogen, nitro, cyano, isothionitro, SR?c, or ORc¿; or R¿2? and R4, taken together, is carbonyl; R3 is R?c¿, alkenyl, alkynyl, ORc, OC(O)Rc, S02R?c, S(O)Rc, S(0¿2)NR?cRd, SRc, NRcRd, NRcCORd, NRcC(O)ORd, NRcC(O)NRcRd, NRcS0¿2Rd, CORc, C(O)ORc, or C(O)NRcRd; R5 is H or alkyl; n is 0, 1, 2, 3, 4, 5, or 6; X is O, S, S(O), S(02), or NRc; Y is a covalent bond, CH¿2?, C(O), C=N-R?c¿, C=N-ORc, C=N-SR¿c?, O, S, S(O), S(02), or NR?c¿; Z is N or CH; one of U and V is N, and the other is CRc; and W is O, S, S(O), S(0¿2), NR?c, or NC(O)Rc; in which each of R?a and Rb¿, independently, is H, alkyl, aryl, heteroaryl; and each of R?c and Rd¿, independently, is H, alkyl, aryl, heteroaryl, cyclyl, heterocyclyl, or alkylcarbonyl. The compounds are useful for treating IL-12 overproduction related diseases (e.g., rheumatoid arthritis, sepsis, Crohn's disease, multiple sclerosis, psoriasis, or insulin-dependent diabetes mellitus).