1. Organic and organometallic chemistry: Transition metal-catalyzed carbene and nitrene transfer reactions are one of most powerful methods for construction of complex molecules in organic synthesis. We have developed some efficient carbene and nitrene transformations and have successfully applied the newly developed methodology in synthesis of bioactive natural products. Gold salts and complexes have emerged as very powerful catalysts for many organic reactions under mild conditions. Due to its exceedingly mild, relatively carbophilic characters, gold can coordinate and activate unsaturated C-C bonds toward nucleophilic attack. We are interested to develop efficient, atom-economic and environmentally benign way for C-C bond formation via gold activation of alkenes or alkynes and to develop new gold complexes capable of activating unactivated alkenes under mild conditions. 2. Green Chemistry: Due to increasing concern on environment and sustainable development of our society, green chemistry have attracted great attention in recent years. My research is aimed to develop efficient green reactions such as direct C-H bond functionalization, multicomponent reaction, photo catalysis and iron catalysis. These reactions could reduce the generation of wastes by avoiding functional group transformation, forming multiple bonds in single operation, using green energy and employing biocompatible metal catalyst, respectively. 3. Chemical biology: Bioconjugation of proteins provides a useful tool for the study of biological systems. However, developing highly chemo- and site-selective reactions for modification of proteins remain a formidable challenge. We are interested to develop new, efficient and selective methods for bioconjugation of proteins based on transition metal-catalyzed reactions. We are also interested to develop new strategy for the study of biology of natural products such as selective conjugation of reporter tag to natural products and rapid building library of natural product analogues.