Lithium bromide acetone complex

In 1910 Serkov (15) determined the conductance of several salts (including lithium bromide) at 25°C in water, methanol, ethanol, acetone, and binary mixtures of these solvents, reporting a value of 144 12 1 cm2 eq-1 for Ao for lithium bromide in acetone. He found that, unlike the other mixtures, acetone solutions exhibit no parallelism between conductance and fluidity, and concluded that when the surveyed ionophores are dissolved in acetone, the complexity of the solvates formed increases as Aq for the ionophores decreases. 

In the laboratory of J. Zhu, the synthesis of the fully functionalized 15-membered biaryl-containing macrocycle of RP 66453 was accomplished. One of the key steps in their approach was Corey s enantioselective alkylation of a glycine template with a structurally complex biaryl benzyl bromide. This benzyl bromide was prepared from the corresponding benzyl mesylate via the Finkelstein reaction using lithium bromide in acetone. 

Jones and colleagues have prepared 1,4-dicarbonyl compounds by conjugate additions of enolate and related anions to a,P-unsaturated sulfoxides [80,81]. For example, the lithium enolate of acetone dimethylhydrazone (83), in the presence of dimethyl sulfide-copper(I) bromide complex, underwent conjugate addition to 2-phenylsulfinyloct-l-ene (82). Quenching the reaction mixture with dimethyl disulfide gave the doubly protected 1,4-diketone derivative (84), which, on sequential hydrolysis with copper(II) acetate and trifluoroacetic acid gave the dodecane-2,5-dione (85) as the product in 54% yield from (82) (Scheme 5.27). Other examples of the addition of enolate-type species to a,p-unsaturated sulfoxides have also been reported [82.83]. 

Some instances of incomplete debromination of 5,6-dibromo compounds may be due to the presence of 5j5,6a-isomer of wrong stereochemistry for anti-coplanar elimination. The higher temperature afforded by replacing acetone with refluxing cyclohexanone has proved advantageous in some cases. There is evidence that both the zinc and lithium aluminum hydride reductions of vicinal dihalides also proceed faster with diaxial isomers (ref. 266, cf. ref. 215, p. 136, ref. 265). The chromous reduction of vicinal dihalides appears to involve free radical intermediates produced by one electron transfer, and is not stereospecific but favors tra 5-elimination in the case of vic-di-bromides. Chromous ion complexed with ethylene diamine is more reactive than the uncomplexed ion in reduction of -substituted halides and epoxides to olefins. ... 

Lithium organocupmtes. House et al. have found that certain undesirable side reactions in the preparation of lithium organocuprates can be minimized by use of this complex rather than commercial cuprous bromide itself, which apparently contains some impurities. The complex is readily prepared in 90% yield from (CH3)2 S and CuBr. It is insoluble in ether, hexane, acetone, methanol, and water, but dissolves in several solvents in the presence of excess (CH3)2S. Thus a solution of the complex in ether and (CH3)2S is used the excess sulfide is readily separated from reaction products. The soluble copper reagent t-BuC CCu can also be used instead of CuBr, but the precursor, t-butylacetylene, is expensive. The use of the complex was illustrated for reactions of (CH3)2CuLi and (CH2=CH)2CuLi. 

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