Compounds of the formula
wherein Y8 is OCH3, OH, NH2, R3COO, R3CONH orCH3S02NH and R3 is an alkyl group having 1 to 5 carbon atoms, a benzyl or phenyl group, and R1 is an alkyl group having 1 to 8 carbon atoms, a benzyl or phenethyl group and R2 is hydrogen or an alkyl group having 1 to 5 carbon atoms or R1 and R2 together form an alkylene group having 4 to 6 carbon atoms, processes for their preparation and/or pharmaceutical preparations and/or methods of treatment employing such compounds. The compounds are useful for treatment of disorders in the central nervous system.