| abstract |
A compound of formula (1): where Ar is a group of formula (Ar-1) or (Ar-2): where R1 is hydrogen or halogen, R2 is hydrogen or alkyl, R3 is hydrogen, alkyl or alkanoyl, R4 is hydrogen, alkyl, alkenyl or alkynyl, X is nitrogen or CH, R5 and R6 are the same or different and each hydrogen or alkyl, and h is 1, 2 or 3; 1 is 1, 2 or 3; m is 1 or 2; n is 0, 1 or 2; o is an integer from 0 to 3, provided that n and or are not simultaneously 0; A is a group selected from the group consisting of (1) to (6): |