Methyl iodide with organometallic compounds

Alkylations of 7i-allylpalladium complexes with organometallic compounds are restricted to the introduction of those alkyl moieties that do not offer the option of / -H elimination1. Efficient methylation of the stoichiometrically prepared complex 147,29 has been achieved with dimethylcadmium and methylmagnesium iodide, while methyllithium leads to preponderant reduction29. Complete retention, as well as exclusive alkylation at the more highly substituted carbon (see Table 25) is observed. 

The reaction of ferrocenylazide and dimethyl e o-cis-3,6-endoxo-A 4-tetrahydrophthalate gives the ferrocenyl compound 68.70 Reaction of cyanoferrocene with trimethylsilyl azide and aluminum chloride gave ferrocenyltetrazole (69) as the sole organometallic product.71 Alkylation of 69 with methyl iodide affords two A-methyl derivatives. The major product is assigned the structure 2-methyl-5-ferrocenyl-tetrazole, while the minor product is assumed to be the 1-methyl isomer. 

An organometallic route to muscarine derivatives has been developed (Scheme 1). Reduction of the aa -dibromo-ketone (1) with Fe2(CO)9 in the presence of DMF provided the furanone (2) in good yield. Acetylation of (2) afforded the corresponding enol acetate, which upon Mannich reaction with dimethylamine and formaldehyde gave the furan derivative (3). Deacetylation followed by dissolving-metal reduction and quaternization with methyl iodide gave two isomeric 4-methyl-muscarine salts (4). These compounds showed physiological properties characteristic of the muscarine alkaloids. 

Reactions of allenes with halides are terminated by attack of organometallic compounds. The reaction of the 2-(2,3-butadienyl)iodobenzene (457) was terminated with alkenyl borane to give 458 [173]. 3-Methyl-1,2-butadiene (459) reacts with ary iodide, and the reaction is terminated by the attack of arylboronic acid 460 to afford 461 [174]. 

Organometallics are formed at the cathode if transient radicals produced in reductions react with the active electrode. This occurs as a side reaction in cathodic coupling (Sect. 12.2, Eq. (185)) of carbonyl compounds, e.g., of acetone 3 9 or of activated olefins, e.g., of methyl vinyl ketone 41or acrylonitrile. Furthermore, in cathodic cleavage (Sect. 13.2, Eq. (227) ) of alkyl bromides or iodides organometallics are formed, e.g., ME(CH2CH2CN)2(ME = Pb, Tl, Sn, Hg) 481 bis(p-substituted benzyl)mercury 485 or dicyclopropylmercury 489 ... 

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