Synthetic organic chemistry enables us to design organic molecules with novel properties and create the desired organic materials. To do this, synthetic organic chemists devote their efforts to develop new bond-forming and bond-breaking reactions. Prof. Tamao's cross-coupling reaction is an efficient method for bond-forming between two components, that normally do not react without catalyst, by using transition metal catalysts. This has become a powerful method for the synthesis of organic molecules that are barely available by traditional methods and has opened up a new access to organic materials for molecular electronics.

In 1970, when Prof. Tamao was a research associate and conducting research on the catalytic functions of nickel complexes, he read a paper on nickel complexes written by Prof. Akio Yamamoto who was a professor at Tokyo Institute of Technology at that time. The paper described the oxidative addition of chlorobenzene to nickel and gave Prof. Tamao the idea that nickel complexes might work as catalysts for carbon-carbon bond formation. The next year, he succeeded to develop a cross-coupling reaction which forms alkylbenzene from an alkyl Grignard and chlorobenzene, which normally do not react because there is no electron exchange between them. By improving the reaction mechanisms, various types of cross-coupling reactions under mild conditions, such as in air and in water, have been developed to play an important role in organic synthesis.

Prof. Tamao has also been conducting research on organosilicon chemistry consistently throughout his career. In the 1970's, it was thought that silicon-carbon bonds could not be cleaved oxidatively because they were stable. However, he thought if he could oxidatively cleave the bonds, it might become an effective basic reaction in organic synthesis. In 1977, he discovered that the silicon-carbon bonds of hexa-coordinate organosilicon compounds could be oxidatively cleaved by meta-chloroperbenzoic acid, and then, in 1982, he discovered that the bonds of tetra-coordinate organosilicon compounds could be cleaved by hydrogen peroxide. This oxidation reaction has become known as the Tamao oxidation.

Later, Prof. Tamao focused on siloles, which are silicon-containing organic ring compounds with a unique electron structure, and developed a method for incorporating silole into pi-electron systems of organic compounds using the cross-coupling reaction. As a result, he developed a general method for synthesizing various silole compounds like pyridyl-silole and oligo-silole. The silole's ability to transfer electrons effectively has already been used in electron-transporting materials for organic EL displays. He says, "Silole chemistry can be regarded as a combination of silicon chemistry and cross-coupling reactions."

Prof. Tamao, who has repeatedly changed the way chemists think, says, "There would be limits in further progress in science and technology without development of new materials. It is the synthetic organic chemists' mission to create new materials with novel properties that are much better than existing materials." He perceives that nanoscience is finally getting to the stage where researchers in different fields such as chemistry and physics can collaborate. He adds that he wants researchers in different fields to understand more about novel materials which synthetic organic chemists create and to use these materials for their research.
(Interviewer: Mayumi Mori, Cosmopia Inc.)

For more information,
http://www.nanonet.go.jp/english/mailmag/2004/034a.html