Methylmagnesium alkoxides

Heitz S, Epping J-D, Aksu Y, Driess M. Molecular heterobimetaHic approach to Li-containing MgO nanoparticles with variable Li-concentrations using lithium-methylmagnesium alkoxide clusters. Chem Mater. 2010 22(16) 4563—4571. 

The progress of the reaction of the quinol alkoxide and methylmagnesium chloride at — 78 C was followed over several hours. Within 5 min the reaction had proceeded to 40-50% completion, with extremely high selectivity (1,4 addition/1,2 addition = 95 1). No... 

In the case of base-induced elimination, the Peterson alkenation relies on the strong bond formed between silicon and oxygen, and the ready propensity for silicon to be attacked by alkoxide, to drive the reaction. In the original study by Peterson, the -silylcarbinols were prepared by the addition of (trimethylsilyl)methylmagnesium chloride to the carbonyl. The caibinols were subsequently eliminated by treatment with sodium or potassium hydride or with sulfuric acid to form the methylene derivatives in excellent yield. The Peterson reaction has proven to be of general utility in the synthesis of alkenes. ... 

Methylmagnesium bromide modified by ZnCl2 reacts with aldehydes in the presence of the Ti alkoxide derived from 51. It leads to chiral 2-alkanols. A Ti(IV) complex of the C2-symmetric isophthalamide 52 and a diastereomer of 42 catalyze the addition of alkynylzinc reagents to aldehydes, whereas the polymer-linked hydroxy-imine 53 alone is used for the same purpose. ... 

The first route attempted for the synthesis of (3J ,4S)-4-methyl-3-heptanol (33, Scheme 8.6) involved cleavage of (R,R)-2,3-butanediol from the intermediate analogous to 26, which failed, but cleavage of (R,R)-2,3-butanediol (l-chlorobutyl)boronate analogous to 25 and esterification with (S,S)-DIPED was successful. Methylation with methylmagnesium bromide yielded only (S,S)-DIPED methylboronate (29), the first evidence of sequential double diastereoselection and the stereodirected alkoxide migration described above (Scheme 8.2) [13]. 

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