1. a Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
2. b Department of Chemistry and the Institute for Genomic Biology , University of Illinois at Urbana-Champaign , 1206 W. Gregory Dr, Urbana, IL 61801, USA
3. c Eisai Inc. , 100 Federal St, Andover, MA 01810, USA