The present invention pertains to certain compounds of Formula (Ia) and pharmaceutical compositions thereof that modulate the activity of the 5-HT2A serotonin receptor. Compounds and pharmaceutical compositions thereof are directed to methods useful in the treatment of platelet aggreagation, coronary artery disease, myocardial infarction, transient ischemic attack, angina, stroke, atrial fibrillation, blood clot formation, asthma or symptoms thereof, agitation or a symptom thereof, behavioral disorders, drug induced psychosis, excitative psychosis, Gilles de la Tourette's syndrome, manic disorder, organic or NOS psychosis, psychotic disorder, psychosis, acute schizophrenia, chronic schizophrenia, NOS schizophrenia and related disorders, and sleep disorders, sleep disorders, diabetic-related disorders, progressive multifocal leukoencephalopathy and the like. The present invention also relates to the methods for the treatment of 5-HT2A serotonin receptor associated disorders in combination with other pharmaceutical agents administered separately or together. ##STR00001##