Polymer-Supported Perruthenate

(reagent used for the oxidation of primary alcohols)

Physical Data: loading 1 mmol g-1 on polymer (batch dependent).

Solubility: cross-linked polystyrene divinylbenzene co-polymer is insoluble in all common aqueous and organic solvents.

Form Supplied in: black powder; commercially available.

Analysis of Reagent Purity: the loading is best determined by the degree of chemical transformation from use of a stoichiometric amount of the reagent. The loading can also be estimated by elemental analysis.

Purification: the polymer is washed successively using water, acetone and dichloromethane, and subsequently dried in vacuo.

Handling, Storage, and Precautions: harmful if inhaled or ingested. Stable at room temperature and may be stored for longer periods of time if kept refrigerated in the dark.

Polymer-supported perruthenate (PSP) is a mild and effective oxidant used mainly for the conversion of primary alcohols to aldehydes. This polymer-supported oxidant can be used either in stoichiometric amounts or as a catalyst in combination with a co-oxidant.1 The reagent is prepared by adding Amberlyst A-26 anion exchange resin (which contains quaternary ammonium groups) to an aqueous solution of potassium perruthenate and sonicating the mixture until the solution turns clear. Alternatively, an aqueous solution of potassium perruthenate can be slowly eluted through a chromatographic column packed with Amberlyst A-26 (prewashed with water, dichloromethane, acetone, and toluene). The resulting black polymer beads are washed successively with water, acetone, and dichloromethane, and dried under vacuum at room temperature. Catalytic oxidations of primary alcohols containing a variety of functional groups can be carried out at room temperature in dichloromethane using N-methyl morpholine N-oxide as the co-oxidant in the presence of 4Å molecular sieves (eq 1).2

Clean oxidations can be carried out using stoichiometric amounts of PSP without the need for additives that result in product contamination. Alternatively, clean catalytic oxidations can be carried out by using molecular oxygen as the co-oxidant. These reactions are normally carried out in toluene (presaturated with oxygen) at 85°C under an atmosphere of oxygen (eq 2).3 After the reaction is complete, PSP can be recovered by a simple filtration and the reduced reagent can be regenerated by external treatment with N-methyl morpholine N-oxide.

Secondary hydroxyl amines can be oxidized to the corresponding nitrones using PSP. Performing the operation in the presence of an electron-poor dipolarophile results in the formation of isoxazolidines through sequential oxidation and [2+3] cycloaddition (eq 3).4

1. Ley, S. V.; Bolli, M. H.; Hinzen, B.; Gervois, A. G.; Hall, B. J., J. Chem. Soc., Perkin Trans. 1 1998, 2239.
2. Hinzen, B.; Ley, S. V., J. Chem. Soc., Perkin Trans. 1 1997, 1907.
3. Hinzen, B.; Lenz, R.; Ley, S. V., Synthesis 1998, 977.
4. Hinzen, B.; Ley, S. V., J. Chem. Soc., Perkin Trans. 1 1998, 1.

Steven V. Ley & C. Ramarao

University of Cambridge, Cambridge, UK

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.