1. Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W., Montreal, Quebec H4B 1R6, Canada
2. Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, Quebec H3A 0B8, Canada
3. Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States