Provided is a compound capable of inhibiting production or secretion of β amyloid protein.A compound represented by the following formula (1): (wherein, R1 represents a heterocyclic group which may have a substituent, R2 represents a cyclic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, R3 represents a cyclic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, R4 represents a hydrogen atom or a C1-6 alkyl group, and X represents —S—, —SO— or —SO2—); an N-oxide or S-oxide thereof; a salt thereof; or a solvate thereof; and a medicament containing any of them.