Lithium triethylborohydride alkyl halides

Tributyltin hydride, 316 Zinc iodide, 280 From alkyl halides Lithium aluminum hydride-Ceri-um(III) chloride, 159 Palladium catalysts, 230 Sodium cyanoborohydride-Tin(II) chloride, 280 From alkyl sulfonates Lithium triethylborohydride, 153 From thiols... 

Lithium triethylborohydride (Super-Hydride) is a much more powerful reducing agent than lithium aluminium hydride. It is useful for the reductive dehalogenation of alkyl halides, but unlike lithium aluminium hydride does not affect aryl halides. It is available as solution in tetrahydrofuran in sealed containers under nitrogen. The solutions are flammable and moisture sensitive and should be handled with the same precautions as are taken with other organometallic reagents (see Section 4.2.47, p. 442). 

Selenides are also nucleophilic and produce isolable selenonium salts (9) when treated with alkyl halides. They are easily oxidized to selenoxides (10) and further to selenones (11) under more forcing conditions (see Section 4). Reduction of selenides to the corresponding hydrocarbons is most conveniently achieved with nickel boride,or with tri-n-butyl- or triphenyltin hydride under radical conditions. " Other reagents for reductive deselenization include Raney nickel, lithium triethylborohydride, and lithium in ethylamine (Scheme 4). Benzylic selenides undergo radical extrusion reactions under thermal or photolytic conditions to produce... 

Li[Et3BH] (Superhydride) (lithium triethylborohydride) Tetrahydrofuran -78 to RT ester —> alcohol ketone —> alcohol aldehyde —> alcohol alkyl halide —> alkane epoxide —> alcohol... 

Table 4 Reduction of Alkyl Halides with Lithium Triethylborohydride in THF ...

Hindered t-alkyl halides with lithium triethylborohydride in the presence of chromous chloride furnish highly crowded coupled products in good yield (equation 111) . Alkanes obtained by hydroalumination of alkenes with LAH in the presence of titanium tetrachloride can be dimerized in the presence of cupric acetate to furnish alkanes (equation 112) ... 

Brown and his co-workers have compared representative simple and complex metal hydrides in order to assess their capabilities for the hydrogenolysis of alkyl halides. Of the reducing agents studied, lithium triethylborohydride is the most powerful, and is the reagent of choice for the hydrogenolysis of alkyl... 

Reactions.—A comparison of various complex metal hydrides and metal hydrides as reagents for the replacement of halogen atoms in alkyl halides by hydrogen has concluded that lithium triethylborohydride and lithium aluminium hydride are of exceptional utility , the former having the greater hydride transfer ability.A review on the replacement of halogen by hydrogen has appeared. ... 

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