1. Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
2. Department of Chemistry & Biochemistry, The University of Texas at Dallas, 800 W. Campbell Rad, Richardson, Texas 75080, United States
3. Abbvie Drug Discovery Science & Technology (DDST), 1 North Waukegan Road, North Chicago, Illinois 60064, United States