(xv) of (xiv) wherein when R2 ' is other than hydrogen and R3 ' is hydrogen, R2 ' is in the 4-, 5- or 6-position; when both R2 ' and R3 ' are other than hydrogen, at least one of them is in the 5- or 6-position and neither of them is in the 7-position; when both R4 ' and R5 ' are other than hydrogen and R5a ' is hydrogen, at least one of R4 ' and R5 ' is in a meta or para position; and when each o