For producing high molecular weight copolymers of ethylene and 1-hexene, a series of siliconbridged fluorenyl-phenoxy group 4 complexes R 2 Si(Flu)(3-t Bu-5-Me-2-C 6 H 2 O)MCl 2 (4a:
The reactions of alkenes with peracetic acid in the presence of RuCls catalyst gave the corresponding -ketols, which are important building units for synthesis of biological active compounds, such as cortisone acetate.-Ketols are important synthetic intermediates and partial structures of various biologically active compounds such as cortisone acetate (l)1 and adriamycin acetate (2).* 12The methods for the synthesis of -ketols from enol ethers3 and enolates4 5have been studied extensively; however, those from olefins are limited to the oxidations with KMnOi-CuSOrSHzO6 7and with isobutylaldehyde/Oa in the presence of OSO4 and bis(3-methyl-2,4-pentanedionato)nickel(II) catalysts.6Recently, we found ruthenium-catalyzed oxidation of amines and amides with peroxides proceeds highly efficiently to give the corresponding -oxygenated products.7•8
dithiophenyl}, were prepared by treating TiCl 4 with the dilithium salts generated by reaction of the corresponding ligands (3, 4, 7, 8, and 11-15) with n BuLi in the presence of Et 3 N in toluene. In the ligand synthesis, the use of, respectively. X-ray crystallographic studies of 6, 17, and 19 indicate that the cyclopentadienyl moiety of 6 with TFCp (TFCp = thiophene-fused cyclopentadienyl) is bound to the titanium atom in an η 5 -fashion, whereas the coordination of the moieties to the metal in 17 and 19 with DTFCp (DTFCp = dithiophene-fused cyclopentadienyl) contributes in somewhat of an η 3 -manner. The newly prepared complexes 5, 6, 9, 10, and 16-20 exhibited high catalytic activities for copolymerization of ethylene and 1-hexene in the presence of i Bu 3 Al/[Me 2 NHPh][B(C 6 F 5 ) 4 ] and afforded higher molecular weight copolymer than the parent tetramethyl-substituted cyclopentadienyl complex Me 2 Si(η 5 -C 5 Me 4 )(3-t Bu-5-Me-2-C 6 H 2 O)TiCl 2 (1a). The complexes 6, 17, and 19 were thermally stable and exhibited high polymerization activities, even at 180 °C. Among tested complexes, the DTFCp complexes 17 and 19 at 180 °C showed very high activity and produced high molecular weight copolymers with good 1-hexene content.
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