abstract |
The invention relates to compounds of formula (I): wherein R<1> represents an alkyl or ureido group, R<2> represents an alkyl group or a hydrogen atom, or R<1> and R<2> together form a 5- or 6-membered ring, R<3> represents a group CN, NO2, NRaR'a, NRaSO2,R'aCZR<5> or CZNRaR'a, R<4> represents a hydrogen atom or a group R<3>. |