. . "In one group of embodiments, the compounds are represented by the formula: ##STR3## in which R1 is C1 -C8 alkyl; R2 and R4 are each independently hydrogen, C1 -C8 alkyl or C1 -C8 alkoxy; R3 is C1 -C8 alkoxy; X11 and Y11 are each independently --Br, --Cl, --OH, --NH2, --OP, and --NHP, wherein P is a suitable protecting group; and q is an integer of from 1 to 4." . .