is substituted or unsubstituted aryl or arylalkyl; and L is a bond. VIIc or VIIIc R.sup.1 is CH.sub.3; X is CH; R.sup.2 is F or Br; R.sup.3 is substituted or unsubstituted aryl or arylalkyl; L is a bond; and R.sup.7 and R.sup.8 are each H. VIId or VIIId