Lithium tributylmagnesate

Treatment of o-dibromobenzene with lithium tributylmagnesate yielded 2-butylphenyl-magnesium reagent, which was formed via benzyne (Scheme 6)". 

Since the carbon-carbon bonds in strained cyclopropane rings have large s-character, cyclopropyl bromides underwent smooth bromine-magnesium exchange by the action of lithium tributylmagnesate (equation 27)". 

Chemists in Banyu Pharmaceutical discovered that lithium tributylmagnesate, prepared from butylmagnesium chloride and two molar equivalents of butyllithium, is quite... 

Preparation of some azulenylmagnesium species was achieved by the halogen-magnesium exchange reactions of iodoazulenes with lithium tributylmagnesate at low temperatures (equations 29-33) . The reactions offer access to a variety of functionalized azulenes including azulenylphosphine, -stannane and -boronic ester. 

Metalation of only the bromine of 2-bromo-3,5-dichloro-6-(trifluoromethyl)-4-trimeth-ylsilylbenzoic acid proceeded smoothly with lithium tributylmagnesate (equation 34). ... 

The reactions of 2-iodopyrazine, 2-methylsulfanyl-4-iodopyrimidine and 3-iodo-6-phenylpyridazine with lithium tributylmagnesate resulted in very efficient iodine-magnesium exchange to yield the corresponding heteroarylmagnesium species (equations 35-37)" °. The reactions with carbonyl compounds and diphenyl disulfide proceeded with good yields. The reactions proceeded smoothly, and neither the starting iodide nor any butylated compounds derived from nucleophilic addition to the heteroaromatic nuclei were observed. 

Treatment of dibromomethyl methyldiphenylsilane with lithium tributylmagnesate at —78°C induced very efficient bromine-magnesium exchange to yield the bromomethylsilane upon protonolysis at —78°C (Scheme 13)" ". Warming the reaction mixture in the presence of a copper salt before protonolysis led to smooth migration of one of the butyl groups to afford 1-silylpentyhnetal. 

Lithium tributylmagnesate induced iodine-magnesium exchange reaction of 5-alkoxy-3-iodomethyl-l-oxacyclopentanes (Scheme 16). A following intramolecular nucleophilic substitution led to construction of a cyclopropane with concomitant opening of the oxa-cyclopentane ring. 

Synthesis of copolysiloxanes 14, a candidate for dental and medical devices and sensors, required the preparation of the substituted allylbenzene 13 (Scheme 20) °. However, attempted cross-coupling reaction of 12 with allylzinc bromide resulted in failure. Alternatively, the magnesiation of 12 with lithium tributylmagnesate followed by the addition of allyl bromide provided 13 in excellent yield. 

One alternative to the halogen-lithium exchange that has been employed in a Parham cyclization is halogen-magnesium exchange, as exemplified by the synthesis of 5-substituted 2,3-dihydrobenzofurans 05)- The use of n-butyllithium is less successful and leads to butylated by products. Lithium tributylmagnesate has also been employed, e.g., 16- 17. ... 

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