This invention is 4-aminopyrimidine derivatives of the formula wherein R1, R2, R3 and R4 are as defined in the specification or a pharmaceutically acceptable salt thereof. The invention also is the preparation of compounds of formula I, pharmaceutical compositions containing therapeutically effective amounts of compounds of formula I or pharmaceutically acceptable salts thereof and to a method of treatment comprising administering therapeutically effective amounts of the compound of formula I for the prevention or treatment of mGluR5 receptor mediated disorders.