156783-24-3Relevant academic research and scientific papers
General Strategy for inducing C-H Bond Fission (Cycloiridation) in Some Aryl, Heterocyclic, Alkenyl or Alkyl Groups in Azines derived from Aldehydes or Methyl Ketones
Perera, Sarath D.,Shaw, Bernard L.,Thornton-Pett, Mark
, p. 1689 - 1696 (1995)
The phosphino hydrazone Z-PPh2CH2C(t-Bu)=NNH2 I has been shown to be a convenient 'reagent' for converting aldehydes or ketones into azines which can be cycloiridated rapidly with C-H bond fission to give iridium(III) hydrides.Condensation of I with a series of substituted benzaldehydes (RCHO) gave mixed azines of type Z,E-PPh2CH2C(t-Bu)=N-N=CHR .The Z,E configuration is necessary for the subsequent cyclometallation and when the azine IIa was treated with in benzene at 75 deg C for 5 min it underwent an aryl C-H bond fission to give the cyclometallated chlorocarbonyliridium(III) hydride 1a.The crystal structure of 1a showed that (i) oxidative addition of the aryl C-H bond to iridium was cis with the hydride ligand trans to chloride, and (ii) the cyclometallated azine ligand was in the terdentate mer arrangement.Azines IIb-IIg reacted similarly.Treatment of IIh with in dichloromethane at 20 deg C effected O-H bond fission to give the O-cyclometallated iridium(III) hydride , which isomerised in benzene at 75 deg C to the C-metallated isomer.Similar treatment of IIi also gave an O-cyclometallated iridium(III) hydride.The phosphino hydrazone I condensed with ferrocenecarbaldehyde to give an azine, which with gave a cyclometallated iridium(III) hydride.Treatment of I with the 2-carbaldehydes of pyrrole, N-methylpyrrole or thiophene or with indole-3-carbaldehyde gave the corresponding azine phosphines with the required Z,E configuration.When the pyrrole azine was treated with the N-cyclometallated chlorocarbonyliridium(III) hydride was formed via a N-H bond fission.The azine phosphines of N-methylpyrrole, thiophene and indole gave C-cyclometallated chlorocarbonyliridium(III) hydrides.Condensation of I with cinnamaldehyde or 3-methylpent-3-en-2-one gave azines which underwent oxidative addition of the olefinic C-H bonds readily to give corresponding C-cyclometallated iridium(III) hydrides.Phosphino hydrazone I also condensed with tert-butyl methyl ketone to give an azine which with gave the C-cyclometallated chlorocarbonyliridium(III) hydride, i.e. metallation in this case occurred on the single methyl group.Proton, 31P- and some 13C- NMR data are given.
