Authors' recent studies concerning the structural effects on the lone pair orientation and electronic state of N-heterocyclic molecules were reviewed. Especially, nonadjacent n, π interacting systems were studied in relation to homoallyl and bishomoallyl interactions. It was concluded that n and π electrons are repulsive in bishomoallyl and bishomobenzyl n, π interacting systems, while these electrons are electronically rather attractive in homoallyl and homobenzyl interacting systems, and that the lone pair electrons prefer the orientation in which the interacting system is more stabilized. Along with these studies, various physico-chemical properties of N-heterocyclic compounds were discussed, i.e., 1H and 13C nmr paramagnetic shifts, magnetic anisotropic effect of lone pair electrons, basicities and ionization potentials.
Various synthetic reactions catalyzed by palladium complexes are classified and explained by typical examples. These reactions include carbonylation, decarbonylation, dimerization of butadiene and isoprene, addition of allene, exchange of allylic and vinylic compounds, addition of olefins, displacement of organic halides, reactions of acetylenes, silanes, and amines.
In the homopolymerization of butadiene, the control of cis, trans and vinyl structure of the polymer was achieved by the nickel catalyst with various electron-donor and electron-acceptor. The author proposed so-called back-biting coordination as a general mechanism for the control of the structure, in which the double bond of the penultimate unit can coordinate to nickel facilitating cis-polymeization and the addition of co-catalyst affects the mode of bidentate of unidentate coordination of butadiene monomer. The copolymerization of diene and monoolefin was succeeded by controlling the available coordination site for bidentate coordination of diene and unidentate coordination of monoolefin. In this way, the alternating copolymer of butadiene and propylene was prepared as an excellent synthetic rubber. The control of mode of dimerization of butadiene was also achieved with zero-valent nickel added by protic compounds with a contorolled strength and a proper amount. In this way, the coupling of butadiene is controlled through proton-transfer or intermolecular insertion reaction. This sort of reaction leads to the related addition reaction of amine, thiol and alcohol to butadiene.
Unique Characteristics and various applications of Cyclodextrins are reviewed with 167 references, especially focusing on formation of their inclusion complexes and recent advances in industrial application of β-Cyclodextrin.
Recent publications on the reactions of hexafluoropropylene oxide (HFPO) were reviewed according to the following items : 1. Preparation of HFPO, 2. Properties of HFPO, 3. Rearrangements of HFPO (3.1 Reactions via pentafluoropropionyl fluoride, 3.2 Preparation of hexafluoroacetone), 4. Nucleophilic reactions, 5. Generation of difluorocarbene, 6. Reactions with perfluoroalkoxide ion.