Methylmagnesium bromide in THF

When y-lactone 14 is treated with methylmagnesium bromide in THF at -78 °C, a carbonyl addition reaction takes place and gives, after aqueous workup, a hemiketal that is subsequently converted to... 

Quinoid imine intermediates also opened avenues to the theoretically interesting 7a-methylcephalosporins (Yanagisawa and Nakao, 1976). Reaction of 200 with methylmagnesium bromide in THF at -78°C afforded a mixture of 7a- and 7p-methylimines, which after hydrolysis to the amines could be separated by chromatography. Routine chemistry produced 7a-methyl- (major) (201) and 7p-methylcephems (202). The configuration at C-7 was confirmed by nuclear Overhauser enhancement (NOE) measurements. 7a-Methyl analog 201 exhibited 17 and 0% NOE values for C-6H-C-7C//3 and C-6//-C-7NH interactions, respectively, whereas 202 showed 5 and 4% NOEs for the same interactions. This methodology was adapted to synthesis of 7-ACA derivatives 203 and 204. 

The bis(methyl) complex, [Mo(0)2Me2(bipy)J, has been synthesized through the reaction of [Mo(0)2Br2(bipy)] with two equivalents of methylmagnesium bromide in THF.23... 

Hydrozirconation of alkynes with the Schwartz reagent Cp2Zr(H)Cl yields the chlorovinyl zirconocene 17, which is easily converted to the methyl vinyl zirconocene 18 with either methyllithium in THF or methylmagnesium bromide in CH2C12. Compound 18 loses further methane at room temperature to form a zirconacyclopropene intermediate 19, which couples with a second alkyne and forms the metallacyclopentadiene 20 (Scheme 6) [34]. 

Ring-opening products derived from primary amines are attractive precursors for the preparation of (3-lactams [57]. With methylmagnesium bromide as the base, diamino esters 33 cyclized readily in THF and stereospecifically generated anti-3-amino- 3-lactams 34 (Table 12.15). 

N-(2-Hydroxy-l-phenylethyl)-N-methyl-l-(4-bromophenyl)ethylamine [16] Methylmagnesium bromide (3 m in ether, 4.8 mmol) is added dropwise to a stirred solution of (2R,4R)-2-(4-bromophenyl)-Al-methyl-4-phenyloxazolidine (1.6 mmol) in THF (15 ml) at -10°. The mixture is stirred at room temperature for 20 h. A small amount of water is added, and the resulting suspension is filtered. The filtrate is dried... 

Reaction of 4 with lithium dimethylcuprate (2 equiv.) in THF effects /3-addition and intramolecular alkylation to 5, but in only 15% yield. Use of methylmagnesium chloride (2 equiv.) and the dimethyl sulfide complex of copper(l) bromide (1 equiv.) increases the yield to 25%. The product is easily dehydrated by TsOH to two isomeric pseudoguaianes (70% yield). 

Preparative Methods phosphorus trichloride is allowed to react sequentially with alkylmagnesium chloride, methylmagnesium bromide, and BH3-THF complex in THF to give... 

The kinetics of the reaction between methylmagnesium bromide and benzophenone in ether/benzene has been explored (77) and a rate process consistent within runs with the kinetic expression, rate = [RMgX] [ketone] reported. Unfortunately over the short concentration spans employed "between runs the k s are inversely proportional to Grignard concentration. In THF the same reaction is second order within a run, if only initial points are considered, the second half of the R groups being utilized very slowly (61). In the ether/benzene system Me2Mg reacts with benzophenone by a process claimed to be third order, but the intended mechanism is not clear, nor do the data support the third-order expression. Initial rates in THF are claimed to be second order (61). 

Dibromo-3-dodecylthiophene (1.28 g, 3.12 mmol) is dissolved in 18 ml of dry THF. Methylmagnesium bromide (3.15 ml, 1.0 M solution in butyl ether) is added and the mixture is heated to reflux for 1 h. Ni(dppp)Cl2 (16.9 mg) is added and the solution is stirred at reflux for 2 h. The mixture is poured into 150 ml of methanol and filtered into a soxhlet thimble. Soxhlet extractions are performed with methanol (to remove monomer and salts), hexanes (to remove catalyst and oligomers), and chloroform. The chloroform fraction is reduced and dried in vacuo to afford 0.510 g (65% yield) of the title polymer as a violet film. 

A soln. of startg. organocerium compd. (prepared from methylmagnesium bromide and CeCl3) added dropwise to a stirred soln. of a-benzyloxyiminoacetophenone (2S,3S)-l,4-dimethoxy-2,3-butylene acetal in dry THF under N2 at —78°, stirred at — 23° to 0° until t.l.c. indicated completion of reaction (1-3 h), and treated with water - 2S-2-benzyloxyamino-1 -phenyl-1 -propanone (2S,3S)-1,4-dimethoxy-2,3-butylene acetal. Y 84% (99% d.e.). F.e.s. H. Fujioka et al., Chem. Pharm. Bull. 37, 602-5 (1989) from aldoximes with RLi/BF3 cf. K.E. Rodriques et al., Tetrahedron Letters 29, 3455-8 (1988). 

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