Grignard reagent partial alkylation with

Alkylation of chlorosilane with a Grignard reagent 459 Partial alkylation of chlorosilane with a Grignard reagent 460 Alkylation of chlorosilane with a Grignard reagent in the presence of a copperlll cyanide catalyst 461... 

A partial mechanism forthe conversion of an alkyl halide to a nitrile, which reacts to form a ketone with a Grignard reagent. 

In a Grignard compound the carbon atom bonded to the electropositive Mg atom carries a partial negative charge. Consequently a Grignard reagent is an extremely strong base, with its carbanion-like alkyl or aryl portion acting as a nucleophile. 

The metal M is commonly magnesium in a Grignard reagent, or lithium, or aluminium, and X is commonly halide. Selective partial alkylation of the tin is usually difficult to achieve, and the reaction is taken to completion to give R4Sn (equation 4-8) if any organotin halides are present, they can be removed as the complexes which they form with dry ammonia, or as the insoluble fluorides which they form with sodium fluoride. Any subsequent dealkylation, if required, can then be achieved by the Kocheshkov reaction (Section 11.1.2). 

The ion pair in eq. (2.10) could revert to reactants, undergo internal transfer of alkyl or halide from the anion to the carbocalion, or react with an external molecule of Grignard reagent. Since the medium is not an hospitable one for ionic species, the lifetime of the ion pair should be short and stereochemistry ntighl be partially preserved, with possible retention of configuration in the internal collapse or inversion in the attack by external reagent. 

CO2). A partial solution to this problem is reaction of the vinyl Grignard reagent with alkyl halides in the presence of cuprous iodide [Cu(I)I], which does little for the initial loss of stereochemistry upon formation of... 

Cook reported the iron/diphosphine-catalyzed alkylation of arene-, heteroarene-, and alkeneamides with primary alkyl halides (Eq. 19) [53] and, shortly after, the alkylation of aromatic amides with benzyl chlorides and secondary alkyl bromides (Eq. 20) [54]. The reaction with primary alkyl bromides proceeded well for aromatic, heteroaromatic, and alkenyl amides despite using phenylmagnesium bromide as a base, the reaction with benzyl chlorides proceeded well under air. As previously observed by Nakamura [28, 34], the slow addition of the Grignard reagent was crucial in order to achieve high yields, presumably because of the competing homocoupling [29]. Secondary alkyl bromides and iodides could be employed in the reaction with benzamides, but acyclic secondary alkyls underwent partial isomerization to the linear alkyl. 

Partial alkylation of chlorosilane with a Grignard reagent (7)... 

---