Abstract: Compounds of the formula ##STR1## wherein R.sub.1 is C.sub.3 -C.sub.8 cycloalkyl, halo-C.sub.3 -C.sub.8 cycloalkyl, C.sub.3 -C.sub.8 cycloalkyl-C.sub.1 -C.sub.6 alkyl, halo-C.sub.3 -C.sub.8 cycloalkyl-C.sub.1 -C.sub.6 alkyl, --Si(R.sub.3).sub.3, --S--R.sub.4, --SO.sub.2 --R.sub.6 or --CO--R.sub.9 ;R.sub.2 is halogen, C.sub.1 -C.sub.4 alkyl or CF.sub.3, the substituents R.sub.2 being identical or different when n is 2;R.sub.3 each independently of the others is C.sub.1 -C.sub.6 alkyl, halo-C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy or phenyl;R.sub.4 is aryl or heteroaryl each of which is unsubstituted or substituted;R.sub.6 is unsubstituted or substituted C.sub.1 -C.sub.10 alkyl, C.sub.2 -C.sub.6 alkenyl, C.sub.2 -C.sub.6 alkynyl, C.sub.1 -C.sub.20 -alkoxy, C.sub.2 -C.sub.6 alkenyloxy, C.sub.2 -C.sub.6 alkynyloxy, C.sub.1 -C.sub.4 alkylthio, aryl, aryloxy or arylthio, or is optionally substituted amino;R.sub.9 is hydroxy, unsubstituted or substituted C.sub.1 -C.sub.10 alkyl, C.sub.2 -C.sub.6 alkenyl, C.