| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Sterically protected 3,4-diphosphinidenecyclobutenes (hereafter abbreviated to DPCB), bearing an extremely bulky 2,4,6-tri-t-butylphenyl group (abbreviated to the Mes^* group), are unique bidentate ligands of interest, because of their relatively rigid framework containing the phosphorus-carbon π-bond. We have prepared various transition metal complexes of DPCB and some of them were used as homogeneous catalysts. We recently prepared 1,2-di(2-thienyl)-3,4-diphosphinidenecyclobutene (DPCB-T) and 1,2-di(3-thienyI)- congener (DPCB-T'), as well as some polymers bearing repeating unit containing the DPCB-T moiety. Both DPCB-T and DPCB-T are promising building blocks for construction of more elaborate DPCB derivatives, because introduction of functional group (at the position a to the sulfur atom) is expected to be easily performed under mild conditions. In fact, various DPCB-T derivatives were prepared by lithiation with butyllithium followed by reaction with electrophiles. Furthermore, mon
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o-and diiodo-DPCB-T derivatives were obtained by successive reactions of DPCB-T with butyllithium and iodoacetonitrile. Further conversions of the iodo-DPCB-T derivatives were then carried out : Various alkynyl groups, such as trimethylsilylethynyl, pyridylethynyl, or azulenylethynyl, were introduced to give new DPCB ligands. Some novel 3,4-diphosphinidenecyclobutenes, bearing thienyl or azulenyl group at the 1,2-positions, were also prepared. In addition, novel spacer was developed as follows. In the course of our continuing researches on developing novel organophosphorus ligands as mentioned above, we interested in the ligand system containing the 2,3-thienylene spacer. The 2,3-thienylene spacer has an advantage : introduction of substituents or functional groups into the 5-position of the thiophene ring is easy. This advantage will help, for example, researches on sophisticated ligands. We then investigated preparations of 1,4-bis(2-ethynyl-3-thienyl)benzene and its application to pyridine ligands, in which the bis(ethynylthienyl)benezene moiety is incorporated as a spacer. Less
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