Patent ID: 7022729

Claim:
Compounds of formula (1) wherein R and R 1 -R 5 are each independently selected from C 1 -C 6 alkyl groups, C 2 -C 6 alkenyl groups, C 2 -C 6 alkynyl groups, C 6 -C 12 aryl-C 1 -C 4 alkyl groups, and C 6 -C 12 aryl groups, wherein R and R 2 -R 5 may also be hydrogen atoms, with the proviso that at least one of R 2 and R 3 and at least one of R 4 and R 5 are other than hydrogen, or R and R 1 together represent a C 3 -C 5 alkylene or alkenylene group, R 2 -R 5 being as defined above; Y is CH; and Z represents a valence bond; and optical isomers and pharmaceutically-acceptable acid and base addition salts thereof.