1. Division of Medicinal Chemistry and Natural Products, School of Pharmacy, C.B. 7360, University of North Carolina, Chapel Hill 27559-7360, N.C., USA
2. Boron Biologicals, Inc., 533 Pylon Dr. Raleigh, 27606, N.C., USA
3. Department of Chemistry and Biochemistry, Utah State University, Logan 84322, Utah, USA