Elbs persulfate oxidation

The oxidation of phenol with potassium persulfate (K2S2O8) in an alkaline medium to p-hydroquinone is known as the Elbs persulfate oxidation. Elbs used ammonium persulfate for the oxidation of 2-nitrophenol (7.42) to 2-nitro-p-hydroquinone (7.43), but the potassium salt is commonly used for the hydroxylation of phenols. 

The Elbs persulfate oxidation procedure was used by Bach and coworiters at an early stage of their syndiesis of model compounds related to fipedericamycin A. Thus the phenol (59) gave 2,5-dihydroxy-4-methoxybenzoic acid (60) in modest yield (30%). This was then transformed in several steps to the isobenzofiiranone (61). Generation of the isobenzofiiran (62) in situ and Diels-Alder reaction of this with the enedione (63) gave, after loss of the trimediylsilyl group, the desired compound (64 Scheme 23) in 62% yield from the isobenzofuranone (61). 

Looker et al used a modification of the Elbs persulfate oxidation procedure in which tetraethyl-ammonium hydroxide was used as the base in their synthesis of S,8-quinoflavone. The phenol (65) was oxidized to the hydroquinone, primetin (66), which upon further oxidation with LTA afforded 5,8-flavo-quinone (67) in 34% overall yield (Scheme 24). 

Elbs persulfate oxidation. Hydroxylation of phenols to p-diphenols by potassium persulfate in alkaline solution. 

One simple example of much-preferred para attack is in the Elbs persulfate oxidation of phenol. The reaction is usually written as the combination of a phenoxy radical 7.123 with the persulfate radical anion 7.126, but it could be phenoxide ion undergoing electrophilic substitution in any event, para attack is substantially favoured over ortho attack.1... 

This reaction is related to the Boyland-Sims Oxidation and Elbs Persulfate Oxidation. 

Other references related to the Elbs persulfate oxidation are cited in the literature. ... 

Also known as the Elbs persulfate oxidation,it is a variant of the Boyland-Sims oxidation except the substrate is phenol rather than aniline. Its mechanism is similar to that of the Boyland-Sims oxidation. 

Elbs Persulfate Oxidation Elbs Reaction Emde Degradation Emmert Reaction... 

Regioselectivity/mechanistic study E. J. Behrman, J. Org. Chem. 57,2266 (1992). Review idem, Org. React. 35, 421-511 (1988). Cf. Elbs Persulfate Oxidation. 

COCH3 Obtained from 2-hydroxy-3-iodo-4-methoxyaceto-phenone oxidised with potassium persulfate in aqueous sodium hydroxide solution (21%) [1924] (Elbs persulfate oxidation). 

Obtained by Elbs persulfate oxidation of 2-hydroxy-4,6-di-methoxypropiophenone (31%) [7405],... 

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