Oxidation Fleming

Fleming, I. Henning, R. Plant, H. J. Chem. Soc., Chem. Commun. 1984, 29. 

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Type I and II silicon-tethered carbonyl-ene reactions were first performed by Robertson.4,4a,4b One particularly striking application of this method is the conversion of isoserine derivative 3 (Scheme 1) into amino triol 4 via a carbonyl-ene reaction followed by Tamao-Fleming oxidation.5... 

Hunt and Roush <1995TL501> achieved a synthesis of swansonine 230 via a stereoselective allylation of a silyl allylboronate derived from tartaric acid followed by a Tamao-Fleming oxidation to introduce the C-2 hydroxy functionality (Scheme 54). 

This reaction, depending on the details of the reaction, is known as the Fleming Oxidation, the Fleming-Tamao Oxidation, the Tamao-Fleming Oxidation, or the Tamao-Kumada Oxidation. 

B. M. Trost and I. Fleming, Oxidation, in Comprehensive Organic Synthesis, Vol. 7, Pergamon, Oxford, 1991. 

The first step of the Fleming Oxidation is the removal of the phenyl group in which the very stable phenylsilane group is converted into a more reactive halosilane after electrophilic aromatic substitution ... 

Like their carbon counterparts, silylcuprates and stannylcuprates readily participate in SN2 -substitution reaction with allylic electrophiles.43,51 For example, <37z//-diastereoselective allylic substitution of the vinyl oxiranes 147 with the lower-order cyanocuprate (PhMe2Si)Cu(CN)Li cleanly affords the allylsilanes 148 (Scheme 38).106 Products of this type can be converted into the corresponding diols with retention of configuration by Tamao-Fleming oxidation 53,53a,53b,107... 

Hydrosilylation, the addition of a Si-H bond across an unsaturated carbon-carbon linkage, is a facile and atom-economical route to organosilanes, which can be functionalized further, for example, using the Tamao or Fleming oxidation protocol [33],... 

The Tamao-Kumada and Fleming oxidation reactions involve the oxidation of specific silyl groups to provide a hydroxyl group with retention of configuration.1... 

An extensive review has been written which covers in detail the oxidation of the carbon-silicon bond under both Tamao and Fleming oxidation conditions.6 One virtue of the use of these procedures as compared to the related oxidation of organoboron compounds is the fact that the silicon groups can often be carried through several synthetic steps while masking the hydroxyl functionality. 

The Fleming oxidation is a two-step process with the second step finding mechanistic similarities in the Tamao oxidation. Principally, treatment of the phenyl(dimethyl)silyl group with HBF4 provides for an electrophilic addition of H+ to the phenyl group to give 5. Attack of the fluoride ion cleaves the carbon-silicon bond, restoring aromaticity in the formation of benzene. 

The Tamao-Kumada and Fleming oxidations have found wide synthetic utility in the oxidation of a variety of silyl groups.6,26 29 However, the true virtue of these reactions lies in the manner in which the silyl group is introduced into the molecule to be oxidized. A number of creative strategies have been developed for this process, some of which will be highlighted below. 

Weinreb and co-workers made use of a nucleophilic hyroxymethyl equivalent in the synthesis of the marine alkaloid lepadiformine.46 A highly stereoselective addition to a-methoxybenzamide 56 was achieved using the silylmethyl cuprate derived from Grignard reagent 57. Exposure of 58 to Fleming oxidation conditions provided 59 in high yield. 

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