1. Department of Chemistry, Stanford University, Stanford, CA 94305‐5080 (USA), Fax: (+1) 650‐725‐0002
2. Merck Research Laboratories: BMB 3‐128, 33 Avenue Louis Pasteur, Boston, MA 02115 (USA)
3. Department of Chemistry, University of Puerto Rico, Río Piedras Campus, PO Box 23346, San Juan, PR 00931‐3346 (USA)
4. Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121 (USA)