Enantiopure Phosphine Oxides with Electron-Rich Chiral Rhenium Stereocenters: Syntheses, Structures, and Brønsted Basicities
Eichenseher S, Friedlein F, O’Brien MJ, Hall MB, Hampel F, Gladysz JA (2025)
Publication Type: Journal article
Publication year: 2025
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Abstract
The chiral racemic methyl complex (η5-C5R5)Re(NO)(PPh3)(CH3) (2) is converted to the rhenium-containing phosphorus donor ligands (η5-C5R5)Re(NO)(PPh3)((CH2)nPR'2) (n/R/R’ = a, 0/H/Ph; 4b, 0/H/t-Bu; 7a, 0/Me/Ph; 10a, 1/H/Ph; 10b, 1/H/t-Bu) via standard sequences involving intermediate phosphonium salts (4a,b and 7a; TfOH/CH2Cl2 or HBF4/chlorobenzene, then PR2H, then t-BuOK; 10a,b, Ph3C+ X−, then PR2H, then t-BuOK). These are converted to the title phosphine oxides (η5-C5R5)Re(NO)(PPh3)((CH2)nP(O)R'2) (n/R/R’ = 1a, 0/H/Ph; 1b, 0/H/t-Bu; 8a, 0/Me/Ph; 11a, 1/H/Ph; 11b, 1/H/t-Bu) using PhIO, Me3SiOOSiMe3 or (for 8a) air. The enantiopure methyl complex (S)-2 is similarly converted to (R)-4a,b, (R)-8a, and (S)-11a,b. The crystal structures of 1a, (S)-1a·(H2O)0.5, (S)-8a, and 11a·CHCl3 are determined. The basicities of PO-containing species play key roles in certain enantioselective catalytic reactions. Those of the title and related compounds are computed by DFT (i.a. 8b > 8a > 1b > 1a > 11b > 11a > t-Bu3PO > Ph3PO). The enhancements in the rhenium-containing species are rationalized.
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APA:
Eichenseher, S., Friedlein, F., O’Brien, M.J., Hall, M.B., Hampel, F., & Gladysz, J.A. (2025). Enantiopure Phosphine Oxides with Electron-Rich Chiral Rhenium Stereocenters: Syntheses, Structures, and Brønsted Basicities. European Journal of Inorganic Chemistry. https://doi.org/10.1002/ejic.202500260
MLA:
Eichenseher, Sandra, et al. "Enantiopure Phosphine Oxides with Electron-Rich Chiral Rhenium Stereocenters: Syntheses, Structures, and Brønsted Basicities." European Journal of Inorganic Chemistry (2025).
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