Functionalization by O-Atom Insertion

To begin to develop functionalization catalysts based on these more electron-rich systems we have been investigating the development of catalytic cycles based on the reaction of O-donor metal-alkoxo complexes with CH bonds as shown in Fig. 7.41 B). This reaction is intriguing because as shown, the reaction leads to the simultaneous CH activation of the hydrocarbon as well as the formation cf a desired oxy-junetionalized product, ROH, in one step. We recently reported [24] the first intermolecular example of such a transformation with trans-(acac-0,0)2lr(0CH3)(CH30H), MeOH-fr-OMe and the corresponding pyridine complex, Py-Ir-OMe. There is no precedent for this type of CH activation reaction with alkoxo complexes [31] and such complexes typically decomposition by facile 8-hydride elimination reactions or formation of inert dinuclear complexes. 

The arene CH activation with these complexes was carried out under an inert atmosphere in neat CgHg (Fig. 7.42) and studies showed that the CH activation product, Ir-Ph [32], is produced. Py-Ir-one provided Ir-Ph in comparable yields but required 4 h and 180 °C. Carrying out the reaction in benzene-dg led to the formation of labeled methanol, CH3OD, in 95% yield (based on added MeOH-Ir-OMe) which was identified by gas chromatography-mass spectrometry (GC-MS) analyses. No other Ci products were detected. The reaction is insensitive to 

Calculations are consistent with the reaction proceeding via the coordination pathway shown in Fig. 7.43. The slower reaction of Py-Ir-OMe compared to MeOH-Ir-OMe is consistent with reversible loss of L since pyridine is a less la- 

MeOH-Ir-OMe and Py-Ir-OMe both catalyze H/D exchange between D2O and C5H5 at 160 °C. The reactions are stable over the time period studied (6 h) and tum-over-frequencies (TOF) of 2.7x10 s were observed based on added MeOH-Ir-OMe. 

We have recently established experimental and theoretical evidence for a facile Re-R to Re-OR bond conversion with non-peroxo YOs that proceeds via a low energy, Baeyer-ViUiger (BV) type, electrophilic O-atom insertion (Fig. 7.44). 

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