1. Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia
2. Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
3. Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, Pennsylvania 17022, United States
4. Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States