prov:value
| - The invention relates especially, on the one hand, to compounds of formula Ia in which R1 is C1 -C4 alkyl, such as methyl, R2 is C1 -C4 alkyl, such as propyl, X is oxy, alk is C2 -C6 alkylene, such as ethylene, 1,3-propylene or 1,4-butylene, n is 1 or preferably 2, R3 is pyrryl, such as 2-pyrryl, or especially thienyl, such as 2-thienyl, or furyl, such as 2-furyl, each of which is unsubstituted or
|