Magnesium tert-butyl bromide

The rate of the reaction decreases with increasing number of substituents in the acetylenic halide, and it is higher with acetylenic bromides than with the corresponding chlorides. Methyl magnesium iodide gives equal amounts of 1,1- and 1,3--substitution products, whereas tert.-butylmagnesium bromide does not react. However, for some tert.-butyl substituted allenes there exists an attractive com-... 

Once the substrate is reduced by a LiDBB (4,4 -di-tert-butyl-biphenyllithium) solution, the transmetallation of the produced lithium enolate is performed with 1 equiv. of the complex magnesium bromide-diethyl ether (MgBr2, Et20) leading to the chelated (Z)-magnesium enolate (equation 25). 

Grignard reagents have been used traditionally as somewhat crude demethylating agents but in the following example demethoxylation was effected in preference to attack of the reagent at the hindered ester site. A 2 1 mixture of phenyl magnesium bromide and 2,6-di-tert-butyl-4-methylphenyl... 

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