819072-61-2Relevant academic research and scientific papers
Preparation of ruthenium azirinyl complexes and reversed regiospecificity of the carbonyl insertion reaction
Lo, Yih-Hsing,Hsu, Sheng-Cheng,Huang, Shou-Ling,Lin, Ying-Chih,Liu, Yi-Hong,Yu, Wang
, p. 5924 - 5933 (2004)
Electrophilic addition of organic halides to [Ru]CN (1; [Ru] = Cp(PPh ]3)2Ru) gave the cationic isocyanide complexes {[Ru]CNCH2R}X (R = CN, 2a; R = CH=CH2, 2b; R = Ph, 2c), which reacted with base (n-Bu4NOH or n-Bu4NF) to give the three-membered-ring azirinyl complexes. For the azirinyl complex with a phenyl group 3c, three isomers, assigned as ruthenium 2H- and 1H-azirinyl complexes, are observed at -20°C. Reaction of the methyl isocyanoacetate complex {[Ru]C≡NCH2COOMe}X (2d) with n-Bu4NOH causes hydrolysis of the ester group to give the ruthenium oxazolone complex 4d. The insertion of the C=O group of acetone, aldehyde, ester, and amide into the C-C bond of the three-membered azirinyl ring of 3a-c yields a variety of five-membered oxazolinyl complexes 5-7. The regiospecificity of the insertion differs from that observed in the photochemically induced carbonyl insertion in the organic azirine system. The diastereoselectivity in the formation of 5-7 is controlled by steric effects. In the formation of the pentamethylcyclopentadienyl oxazolinyl ruthenium complex 7a*, the intermediate 8a* is isolated before cyclization. Molecular structures of 7a* and 8a* have been determined by single-crystal X-ray diffraction analysis. Treatment of 7 with hydride gave [Ru]CN and alcohol.
