Disclosed are compounds of the Formula (I) and pharmaceutically acceptable salts and prodrugs thereof, wherein A, B, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are as defined in the specification. Such compounds are tyrosine phosphatase inhibitors and useful in the treatment or prevention of Type II Diabetes Mellitus. Also encompassed by the invention are formulations comprising the noted compounds, processes for preparing such compounds, a method for treating or preventing Type II Diabetes Mellitus. 1