re I and is a member selected from the group consisting of H and DA, wherein D is attached to the ring and is a member selected from the group consisting of O, S and NH and A is attached to D and is represented by structure III: ##STR24## wherein Z represents (1) a double bond with at least one H being attached to C1 and an H or halogen being attached to C2, or (2) a triple bond; and E is a member