The present invention is related to a compound of formula (I) wherein R1, R2, R3 and R4 are as defined herein, or an addition salt of an acid thereof, the pharmaceutical composition and preparation thereof, and the therapeutic use thereof in the treatment or the prevention of diseases involving Nurr-1 nuclear receptors, also known as NR4A2, NOT, TINUR, RNR-1 and HZF3.