2,3,4,4a-tetrahydro-1h-pyrazino(1,2-a)quinoxalin-5(6h)one derivates being 5ht2c agonists

This invention provides compounds of formula (I), and enantiomers thereof, wherein R is hydrogen or alkyl of 1-6 carbon atoms; R' is hydrogen, alkyl of 1-6 carbon atoms, acyl of 2-7 carbon atoms, or aroyl; R1, R2, R3, and R4 are each, independently, hydrogen, alkyl of 1-6 carbon atoms, alkoxy of 1-6 carbon atoms, halogen, trifluoroalkyl, -CN, alkyl sulfonamide of 1-6 carbon atoms, alkyl amide of 1-6 carbon atoms, amino, alkylamino of 1-6 carbon atoms, dialkylamino of 1-6 carbon atoms per alkyl moiety, trifluoroalkoxy of 1-6 carbon atoms, acyl of 2-7 carbon atoms, or aroyl; X is CR5R6 or a carbonyl group; R5 and R6 are each, independently, hydrogen or alkyl of 1-6 carbon atoms; or a pharmaceutically acceptable salt thereof, with the proviso that at least one of R1, R2, R3, or R4 are not hydrogen; which are 5HT2C receptor agonists useful for the treatment of disorders involving the central nervous system such as obsessive-compulsive disorder, depression, anxiety, schizophrenia, migraine, sleep disorders, eating disorders, obesity, type II diabetes, and epilepsy.