Bromophosphatation as a Mode of Chiral Phosphoric Acid Catalyst Deactivation as Elucidated by Kinetic Profiling
DOI: 10.14469/hpc/14708 Metadata
Created: 2024-10-31 15:27
Last modified: 2025-04-16 16:42
License: Creative Commons: Attribution + Non Commercial 4.0
Funding: (none given)
Co-author: Ben Lancaster Co-author: Christopher J Tighe Co-author: D. Christopher Braddock
Description
A BINOL-derived chiral phosphoric acid 1 has been shown to deactivate during the catalytic bromoesterification of cyclohexene. Further investigation revealed that this is due to an alkene bromophosphatation process, where the phosphate of 1 acts as a competitive nucleophile forming bromoalkylated phosphate 3 as a 56:44 mixture of (R,1R,2R)- and (R,1S,2S)-diastereomers. HPLC separation of the diastereomers gave pure (R,1R,2R)-3 whose structure was proven by single-crystal X-ray diffraction. The 31P{1H} NMR spectrum of phosphate (R,1R,2R)-3 had four peaks despite 3 having just one phosphorus atom, and DFT analysis revealed this to be a consequence of rotational isomerism about the C3,3’−Ar bonds. VTNA studies of the catalytic cyclohexene bromoesterification showed that it is first order in all the reactants and catalyst 1, enabling us to refine the mechanism for this process.
Members
| DOI | Description |
|---|---|
| 10.14469/hpc/14924 | DFT Results |
| 10.14469/hpc/14823 | (1S,2S)-(+)-2-Bromocyclohexyl benzoate (2) |
| 10.14469/hpc/14824 | Bromocyclohexyl phosphates 3a+3b, 3a and 3b |