Combination of Reactions and Separations for New Organic Synthesis

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The purpose of organic synthesis is to produce useful organic compounds with high efficiency. Organic chemists have tended to focus on the efficiency of reactions and competence of synthetic strategies. It is important to recognize, however, that total efficiency of synthesis is also limited by the ability to separate and isolate products in a pure form. Although substantial efforts have been made to develop new efficient reactions, it is highly necessary to develop strategic separation protocols that are generally applicable for various structural types of compounds. The purpose of this research is developing a new combination of strategic separation protocol and reactions to enhance the ability of organic synthesis.We focused on acid-base extraction and found that 2-pyridyldimethylsilyl group serves as an effective phase tag for this purpose. The introduction of the tag to organic molecules can be easily accomplished by hydrosilylation and the reaction with 2-pyridylsilylmethyllithium. Carbometallation (Mizoroki-Heck reaction) to alkenylpyrilylsilane and alkynylpyridylsilane can also be utilized for the synthesis of tagged compounds. The removal of the tag can be accomplished by Tamao oxidation and Hiyama cross-coupling reaction.With the tag in hand, we have developed diversity oriented synthesis of biologically active compounds such as tamoxifen type tetrasubstituted olefins. We also developed new methods for the construction of extended π-electron systems, which exhibit interesting photophysical properties such as photo luminescence. By using difunctional and trifunctional aryl halides in Mizoroki-Heck reactions and cross-coupling reactions, unique polymers and dendrimers of extended π-electron systems were synthesized.