Two precatalysts for application in propargylic CH activation

Abstract

The complexes {bis[(2‐diphenylphosphanyl)phenyl] ether‐κ2P,P′}(η4‐norbornadiene)rhodium(I) tetrafluoridoborate, [Rh(C7H8)(C36H28OP2)]BF4, and {bis[(2‐diphenylphosphanyl)phenyl] ether‐κ2P,P′}[η4‐(Z,Z)‐cycloocta‐1,5‐diene]rhodium(I) tetrafluoridoborate dichloromethane monosolvate, [Rh(C8H12)(C36H28OP2)]BF4·CH2Cl2, are applied as precatalysts in redox‐neutral atomic‐economic propargylic CH activation [Lumbroso et al. (2013). Angew. Chem. Int. Ed.52, 1890–1932]. In addition, the catalytically inactive pentacoordinated 18‐electron complex {bis[(2‐diphenylphosphanyl)phenyl] ether‐κ2P,P′}chlorido(η4‐norbornadiene)rhodium(I), [RhCl(C7H8)(C36H28OP2)], was synthesized, which can form in the presence of chloride in the reaction system.

Selective Catalysts for the Homogeneous Semi‐Hydrogenation

“…By layering n ‐heptane (5 mL), an orange‐yellow solid was obtained, which was filtered off and washed twice with n ‐heptane (4 mL). 1 H and 31 P NMR spectra are in line with the literature [14] …”

“…[Rh(Cl)(DPEPhos)(NBD)] [14] [Rh( μ ‐Cl)(DPEPhos)] 2 (20 mg, 0.015 mmol) was dissolved in THF (3 mL) and subsequently mixed with NBD (700 μL). The reaction mixture was stirred for 2 h at room temperature.…”

“…1 H and 31 P NMR spectra are in line with the literature. [14] [Rh(Cl)(DPPP)(COD)] [13] [Rh(μ-Cl)(COD)] 2 (17.3 mg, 0.035 mmol) and DPPP (28.9 mg, 0.070 mmol) were dissolved in THF (3 mL). After stirring for 2 h at room temperature, the orange solution was layered with diethyl ether and stored at 5 °C.…”

Catalyst Deactivation During Rhodium Complex‐Catalyzed Propargylic C−H Activation

“… [10a] However, the results also indicate that the alkyne complex 14 is not asymmetric, as previously assumed but has a symmetrical structure and is neutral in nature due to the coordination of two alkyne molecules. [20] Based on NMR data (d, δ =23.3 ppm, J RhP =117 Hz) and comparison with literature data ([RhCl(NBD)(DPEPhos)], d, δ =15.5 ppm, J RhP =120 Hz), [21] this compound is most likely a rhodium(I) complex that possesses a fivefold coordinated metal center (Figure S26). Furthermore, its formation is reversible.…”

Activation, Deactivation and Reversibility Phenomena in Homogeneous Catalysis: A Showcase Based on the Chemistry of Rhodium/Phosphine Catalysts

“…When [Rh(NBD) 2 (µ 2 -Cl)] 2 is reacted with DIPAMP under the same conditions, a cationic complex results almost quantitatively, in which the rhodium center is coordinated by two DIPAMP molecules and the chloride acts as a counterion ( Figure 2b) [38]. With DPEPhos a species is formed in which the diphosphine, the diolefin, and a chloride ligand bind to rhodium to give a penta-coordinated complex ( Figure 2c) [50]. Similar coordination compounds of the form [Rh(disphosphine)(diolefin)Cl] have been reported as well and discussed in detail [38,39].…”