Please use this identifier to cite or link to this item:
Title: Mechanism and stereochemistry of diphosphate formation from dioxaphosphorinanes: A critical reassessment.
Authors: Cullis, P. M.
Fawcett, J.
Griffith, G. A.
Harger, M. J. P.
Lee, M.
First Published: 2001
Citation: Journal of the American Chemical Society, 2001, 123 (18), pp.4147-4154
Abstract: The mechanism of diphosphate formation from (R)-2-chloro-2-oxo-5,5-dimethyl-4-(R)-phenyl-1,3,2-dioxaphosphorinane (5a) and 2-hydroxy-2-oxo-5,5-dimethyl-4-(R)-phenyl-1,3,2-dioxaphosphorinane (6) has been investigated. The products formed are the ax−ax diphosphate 7a and the ax−eq diphosphate 7b, with no evidence in the 31P NMR spectrum for pentacoordinate chlorooxyanionic phosphoranes 9. The structure of 7b has been established unambiguously by NMR spectroscopy, mass spectrometry, and elemental analysis, and the structures of 5a and 7a have been confirmed by X-ray crystallography. The mechanism of the crucial diphosphate-forming reaction has been probed using 18O-labeling studies. The 18O-labeling patterns are consistent with the unsymmetric ax−eq diphosphate 7b arising from selective nucleophilic attack of the axial oxygen of 6 on the chloride 5a with inversion of configuration at phosphorus. The symmetric ax−ax diphosphate 7a can be formed directly, as a result of selective nucleophilic attack of the axial oxygen of 6 on the chloride 5a with retention of configuration, but the majority arises indirectly by isomerization of the ax−eq diphosphate 7b. The isomerization apparently involves intermolecular exchange, with nucleophilic attack of the phosphate anion 6 on the equatorially substituted phosphorus atom of 7b with inversion of configuration at phosphorus.
DOI Link: 10.1021/ja004084n
ISSN: 0002-7863
Type: Article
Appears in Collections:Published Articles, Dept. of Chemistry

Files in This Item:
There are no files associated with this item.

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.