Sodium Barbier reaction

When reacted with allyl/propargyl bromide in the presence of indium and sodium iodide, isatins undergo efficient allylation/propargylation to afford the corresponding 3-substituted 3-hydroxy-oxindoles (Scheme 50).206 Indium-mediated Barbier reaction of ninhydrin with benzyl bromide in DMF gives 45 and O-benzylated compound 46. Similarly, the reaction of isatin with allyl bromide affords 47 and 48.207... 

In these reactions, only the initial and final substances have been indicated. It is possible that the actual mechanism of the reaction is not so simple and that it takes place in several stages. Evidence for this view is to be found in an analogous reaction, in which magnesium is used in place of sodium. This reaction can be used in a great number of syntheses and is generally known as the Barbier-Grignard reaction. The ordinary formulation is as follows ... 

With isocyanates (Eq. 72) a Barbier reaction leading to aromatic amides from an aryl bromide is best done with sodium. ... 

It may be of interest here to report that attempts to prepare patchouli-alcohol via an intramolecular Barbier reaction of a haloketone with magnesium were unsuccessful [76], [77] but that executing this reaction in a sealed tube with sodium in THF at 100 °C gave the required product (see Sect 3.2 for Na-Barbier reactions) ... 

Although the number of applications of sodium in one-step processes is limited, some Na-Barbier reactions are worth mentioning here. 

In 1972, in a follow-up to the first paper on this Li-Barbier reaction [15], also the use of sodium in this type of reaction was studied. It was reported that there was a significant diminution in the yields of alcohols that was particularly true of carbonyl compounds which possessed a-hydrogen atoms. 

The use of substoichiometric amounts of an arene (naphthalene or biphenyl) was first studied in the reaction of bromobenzene and benzaldehyde with sodium, under Barbier-type reaction conditions The possibility of using a substoichiometric amount of DTBB... 

Organophosphorus compounds find wide use in the chemical industry as catalysts, intermediates, complexes, and end-use products. Arylphosphines and phosphine oxides are often produced by the reaction of a preformed Grignard reagent with a halophosphine or phosphine oxide. Yields are reduced by the production of unwanted side-reaction products such as biaryls. These unwanted products are reduced when the reaction is conducted under Barbier conditions. When alkyl and aryl halides are reacted with magnesium metal, a trihalophosphine or phosphine oxide, a metal halide or amine catalyst, in THE benzene mixtures, at reflux, good yields of phosphines or phosphine oxides are obtained [74]. For example, triphenylphosphine can be prepared in a 97.2% yield from the reaction of bromobenzene, trichlorophosphine, magnesium metal, aluminum chloride, and sodium chloride in THF-benzene at 70 80 C. 

In 1895, four years before Barbier s report [6] on the one-step synthesis with magnesium, sodium was used in a one-pot reaction with bromobenzene and ethyl oxalate, the unforeseen product being triphenylmethanol [7]. 

In 1968, sodium was successfully applied [12] for the following cyclization reaction (intramolecular Barbier-type reaction) which had previously failed with magnesium ... 

Recently sodium was used in a Barbier-type reaction [16] with bromobenzene and tert-hutyl isocyanate in THF and a stoichiometric amount of HMPA (using sonication, ))), to promote the reaction) ... 

Preparative Methods [difluoro(phenylthio)methyl]trimethyl-silane (PhSCF2SiMe3) was prepared for the first time by Prakash et al., using the Barbier coupling reaction of bromodi-fluoromethylphenyl sulfide, prepared from dibromodifiuoro-methane and sodium benzenethiolate, magnesium metal, and chlorotrimethylsilane (TMSCl) in DMF (eq 1). 

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