Methylmagnesium halides

The Grignard reagent attacks the unsaturated ketones (3) and (6) from the relatively unhindered ot- or jS-side, respectively, perpendicular to the plane of the conjugated system. An analogous transition state (10) leading to axially substituted 1,6-addition products (11) from A -3-ketones (9) with methylmagnesium halide was suggested by Marshall. ... 

Reaction of methylmagnesium halide with the 6-ketones (26), (27) and (28) yields the 6a-methyl-6/ -hydroxy compounds. 

Electrochemical synthesis was utilized to prepare labeled compounds. Tetramethyllead labeled with 14C was prepared in a double compartment cell in DMF with NaClC>4, by electrolyzing 14CH3l on lead electrodes. The method is reported as superior to transmet-allation with methylmagnesium halide. It is also possible to incorporate lead isotopes. 2i°Pb2+ ions were deposited on a Cu foil and the latter was used as a sacrificial electrode in solutions of CH3I. The yield of labeled tetramethyllead was 85%65. Synthesis of 210Pb-labeled chlorotrimethylplumbane was also described66. 

Trimethylpyrylium perchlorate has been prepared from 2,6-dimethylpyrone and methylmagnesium halides 6 from mesityl oxide and sulfoacetic acid 6 from mesityl oxide (or less satisfactorily from acetone) and a mixture of acetic anhydride and perchloric acid 7 from mesityl oxide, acetyl chloride, and aluminum chloride 8 and from <-butyl chloride, acetyl chloride,... 

Grignard reaction, of methylmagnesium halides with 2,6-dimethylpyrone, 44, 102 (... 

N-Methylisobutylamine, 44, 77 Methyl isocyanide, 41, 15 N-Methylisopropylamine, 44, 77 Methylmagnesium halides, reaction with... 

Tetramethylbiphosphine disulfide has been prepared by reaction of methylmagnesium halides with thiophosphoryl chloride. ... 

To make any secondary alcohol, however, there is often a choice of two possible routes, depending on which part of the molecule you choose to make the organometallic and which part you choose to make the aldehyde. For example, the first example here shows the synthesis of a secondary alcohol from isopropylmagnesium chloride and acetaldehyde. But it is equally possible to make this same secondary alcohol from isobutyraldehyde and methyllithium or a methylmagnesium halide, acetaldehyde isobutyraldehyde... 

On the whole, reactions of thioketones with vinyl-, allyl-, propargyl-, benzyl-, and, sometimes, methylmagnesium halides proceed by carbophilic addition [1-3] (though subsequent rearrangements to the thiophilic product may occur [2]) ... 

Prepared by treating -nitrobenzaldehyde with a methylmagnesium halide and oxidizing the resulting carbinol with chromic acid. Beelingozzi, Atti accad. Lincei i9> 332 (1934) [C. A. 28, 5053 (i934)l-... 

In a similar manner, Grignard reagents react with cyclic a,/3-dihalo ethers derived from 3,4-dihydro-l,2-pyran and tetrahydrofuran to form the corresponding 2-alkyl-3-halo derivatives. Thus, addition of 2,3 dibromotetrahydropyran to methylmagnesium halide at 0° followed by hydrolysis gives a 65% yield of 2-methyl-3-bromotetrahydropyran. These materials are valuable intermediates in the synthesis of olefinic alcohols (cf. method 99). 

The cleavage of pyrazine ethers with acid, alkali, methylmagnesium halides, and catalytic hydrogenation has been described in Section ID and chloro and bromo substituents have been introduced into various alkoxypyrazines as described in Sections V.1A(3) (155), V.1B(3) (814), V.IE (844), and V.2A (898). 

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