Lithium metal, reaction with methyl chloride

In the absence of alcohol the reduction may be halted at the dihydro stage, but with difficulty. Stoichiometric control (3 equiv. of metal) gives reasonable results, but it seems to be most effective to use 5 equiv. of lithium with added iron(III) chloride. Thus, from the reduction of (112), quenching with ammonium chloride gives either the 1,2- or 1,4-dihydro products (114) and (115), respectively, while reaction with methyl iodide affords excellent yields of the 2-methyl-1,2-dihydro derivatives (113 Scheme 20). 

The reaction of an organic halide with a metal is an oxidation-reduction in which the metal is the reducing agent. As shown in the fohowing equahons for the reactions of methyl chloride with lithium and with magnesium, a single-electron transfer from the metal converts methyl chloride to a radical anion, which then dissociates to a methyl radical and chloride ion. Bond formahon between methyl radical and a metal species ( Li or Mg" ) follows. 

Chiral oxazolidines 6, or mixtures with their corresponding imines 7, are obtained in quantitative yield from acid-catalyzed condensation of methyl ketones and ( + )- or ( )-2-amino-l-phcnylpropanol (norephedrine, 5) with azeotropic removal of water. Metalation of these chiral oxazolidines (or their imine mixtures) using lithium diisopropylamide generates lithioazaeno-lates which, upon treatment with tin(II) chloride, are converted to cyclic tin(II) azaenolates. After enantioselective reaction with a variety of aldehydes at 0°C and hydrolysis, ft-hydroxy ketones 8 are obtained in 58-86% op4. 

A second approach involves a nucleophilic attack on the metal. This is seen in the reaction of methyl lithium with tungsten(V ) chloride ... 

Ignition on contact with furfuryl alcohol powdered metals (e.g., magnesium iron) wood. Violent reaction with aluminum isopropoxide -f- heavy metal salts charcoal coal dimethylphenylphosphine hydrogen selenide lithium tetrahydroaluminate metals (e.g., potassium, sodium, lithium) metal oxides (e.g., cobalt oxide, iron oxide, lead oxide, lead hydroxide, manganese oxide, mercur oxide, nickel oxide) metal salts (e.g., calcium permanganate) methanol + phosphoric acid 4-methyl-2,4,6-triazatricyclo [5.2.2.0 ] undeca-8-ene-3,5-dione + potassium hydroxide a-phenylselenoketones phosphorus phosphorus (V) oxide tin(II) chloride unsaturated organic compounds. 

In another synthesis the diol 155 was oxidized with silver carbonate on Celite to the lactone 156 convertible (lithium dimethyl cuprate, debenzylation, and dehydration) to ( )-eldanolide [( )-129]. Finally a synthesis of racemic eldanolide involved coupling of a C4 unit, 157, with 4-methyl-3-pentenal. In tetrahydrofuran at -78 C, the reaction occurred at the y-position to the metal atom (158) to yield 72% of the alcohol 159, which gave 98% ( )-129 with mercuric chloride. ... 

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