S43 Synthetic Organic Chemistry in Drug Discovery: New Concept and Methodology for the Construction of Organic Molecules S43-1 Transition metal-catalyzed [2+2+2] cycloaddition of alkynes with arynes or hetarynes S43-2 Mysterious Relationship between Halogen and Metals: Novel Synthesis of Halogenated Compounds S43-3 Synthetic studies on natural products derived from amino acids using cycloaddition reactions of a nitrone S43-4 Synthetic investigation of catechins for development of probe molecule S43-5 Total synthesis and biological evaluation of natural products S43-6 Chemistry in the synthesis of polycyclic nitrogen containing natural products-failure is a stepping-stone to success S43-7 A new strategy for the synthesis of highly substituted alkaloids