Referring to an oxazine Derivative of formula (a), (b) or (c). It also relates to a Pharmaceutical composition. These compounds are of bace Inhibitory activity and are useful in the treatment of Neurological Disorders such as Alzheimers diseaseREFERIDA A UN DERIVADO DE OXAZINA DE FORMULA (a), (b) O (c). TAMBIEN ESTA REFERIDA A UNA COMPOSICION FARMACEUTICA. DICHOS COMPUESTOS TIENEN ACTIVIDAD INHIBIDORA DE BACE Y SON UTILES EN EL TRATAMIENTO DE TRASTORNOS NEUROLOGICOS TALES COMO LA ENFERMEDAD DE ALZHEIMER