Abstract: Disclosed are compounds of compounds of the formula: or the pharmaceutically acceptable nontoxic salts thereof wherein:X is oxygen, H.sub.2 or sulfurY is hydrogen, or optionally substituted alkyl, alkenyl, (substituted)arylalkyl, aryl or heteroaryl, or a carbonyl group substituted with alkyl, cycloalkyl, aryl, or amino groups;W is alkyl, arylalkyl or heteroarylalkyl, where each aryl group is optionally substituted with up to two groups; orW is aryl, thienyl, pyridyl or heteroaryl, each of which is optionally substituted; andZ.sub.1, Z.sub.2, Z.sub.3, and Z.sub.4 independently represent nitrogen or C-R.sub.1 where R.sub.1 is hydrogen, halogen, hydroxy, amino, or phenyl or pyridyl optionally mono- or independently disubstituted with halogen, hydroxy, lower alkyl, or lower alkoxy,which compounds are highly selective agonists, antagonists or inverse agonists for GABAa brain receptors or prodrugs of agonists or inverse agonists for GABAa brain receptors.