[1] Agcy Sci Technol & Res, ICES, Chem Synth Lab Biopolis, Singapore 138667, Singapore
[2] Scripps Res Inst, Dept Chem, La Jolla, CA 92037 USA
[3] Scripps Res Inst, Skaggs Inst Chem Biol, La Jolla, CA 92037 USA
[4] Univ Calif San Diego, Dept Chem & Biochem, La Jolla, CA 92093 USA