Courtney C Aldrich1, Félix Calderón2. 1. Department of Medicinal Chemistry, College of Pharmacy , University of Minnesota , 8-174 Weaver-Densford Hall, 308 Harvard Street S.E. , Minneapolis , Minneosta 55455 , United States. 2. Tres Cantos, Medicines Development Campus, DDW, GlaxoSmithKline, Severo Ochoa 2 , Tres Cantos , Madrid 28760 , Spain.