Ketones organometallic reagent attack

Acceptor ability of a group can be enhanced by interaction with a suitable electrophile (proton, Lewis acid). This is very likely in the Ni(acac)2-catalysed reaction of cyclopropyl ketones with trimethylaluminium and in the synthetically more significant addition of several cuprates to alkyl cyclopropyl ketones. The BFs-activated organometallic reagent attacks the less substituted cyclopropane carbon regioselectively. Yet steric hindrance can be a problem in this reaction (equation 40) . 

Ketones may be prepared in high yield from acyl chlorides and organomanganous iodides since these organometallic reagents attack ketones very slowly. Aldehydes are of intermediate reactivity, whereas esters are inert.The reaction of an a-monosubstituted acetyl chloride with Fe2(CO)9 is a mild general means of preparing symmetrical dialkyl ketones in fairly good yield (Scheme 8). ... 

Organometallic reagents attack nitriles to give ketones... 

The initial formation of an ate complex by attack of the nucleophile on the aluminum reagent, followed by reaction with the ketone, is unlikely since treatment of the ketone with a mixture of MAD and the organometallic reagent gave results comparable to those obtained with the organometallic reagent in the absence of MAD. 

Lich reaction simply involves the nucleophilic attack of the organometallic reagent on the aldehyde rr ketone followed by protonation. You may draw the intermediate as an anion or with an O-metal ->nd as you please. Note the atom-specific arrows to show which atom is nucleophilic. In the second example the allyl-lithium might attack through its other end. 

The acyliron(0) complex (102) has been isolated and subjected to the same nucleophilic displacement (or equivalently oxidative addition) with excellent correlation (Scheme 39). The same species is also readily available from acid chlorides (i.e. formation of 103), but the overall process has not been widely used in the synthesis of ketones (Scheme 40). The final step of the process, a reductive elimination of acyliron(II) complex (104) or (105), is quite rapid and it has not been possible to isolate and identify the presumed intermediates in this case (Scheme 41). Since the oxidative addition of the acyliron complex with the alkyl halide is extremely mild, the corresponding ketone formed in the reaction is not subject to attack by organometallic reagents and no tertiary tdcohol is formed. 

In a number of reactions, such as those leading to amidines and the formation of ketones by reaction with organometallic reagents, the cyanopyridines behave normally, and these call for no comment. The simultaneous attack of propyl magnesium bromide on the cyano group and C(4) in nicotinonitrile has been mentioned (p. 200). 

In Summary The carbonyl group in aldehydes and ketones can be attacked by carbon-based nucleophiles. Organometallic reagents give alcohols and cyanide gives cyanohydrins. 

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