Compounds of formula (1); wherein R.sub.1 is optionally substituted C.sub.1-C.sub.3alkyl C.sub.2-C.sub.3alkenyl, or C.sub.2-C.sub.3alkynyl, or --NR.sub.6R.sub.1, --ORB, --SR.sub.9 or halogen; R.sub.3 is II; optionally substituted C,-Csalkyl, C.sub.2-C.sub.6alkenyl, C.sub.2C.sub.6alkynyl, or C.sub.3-C.sub.7 cycloalkyl, halogen; OH or OR.sub.10; R.sub.4 is H, optionally substituted C.sub.1C.sub.6alkyl, C.sub.3-C.sub.6alkenyl, C.sub.3-C.sub.6alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl or heteroaryl, R.sub.5 is H or Optionally substituted C.sub.1-C.sub.6alkyl, C.sub.3-C.sub.6alkenyl, C.sub.3-C.sub.6alkynyl, or C.sub.3-C.sub.7 cycloalkyl; or R.sub.4 and R.sub.5 together form a 5 or 6-membered heterocyclic ring; and R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are optionally substituted C.sub.1-C.sub.3alkyl, C.sub.2-C.sub.3alkenyl, C.sub.2-C.sub.3alkynyl, or C.sub.3-C.sub.7 cycloalkyl; are purine receptor, particularly adenosine receptor antagonists, useful for treatment of, inter alia, movement disorders such as Parkinsons disease.