Preparation of Ruthenium Azirinyl Complexes and Reversed Regiospecificity of the Carbonyl Insertion Reaction
Resource
Organometallics 23 (25): 5924-5933
Journal
Organometallics
Journal Volume
23
Journal Issue
25
Pages
5924-5933
Date Issued
2004
Date
2004
Author(s)
Abstract
Electrophilic addition of organic halides to [Ru]CN (1; [Ru] = Cp(PPh3)2Ru) gave the cationic isocyanide complexes {[Ru]CNCH2R}X (R = CN, 2a; R = CHCH2, 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 CO 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.
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journal article
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