Organic electrophiles Grignard

Grignard reagents are least tolerant of common organic electrophilic functional groups, such as carbonyl and nitro groups, while organoboron compounds tolerate most such electrophiles. 

Imido complexes can also be formed from metal-nitrido species by alkylation of the nitrogen (Equation 13.61). Electron-rich nitrido species undergo alkylation with organic electrophiles, such as alkyl halides and trimethyloxonium reagents. Electron-poor nitrido species undergo alkylation with carbon nucleophiles, and an example of the alkylation of a metal-nitride by a Grignard reagent is shown in Equation 13.62.257... 

We foimd that aryl bromide (TFVE-Br) underwent smooth and quantitative metal-halogen exchange with /-butyllithium in ether at -78°C. The aryllithium reagent reacted readily in ether solution at low temperature with a variety of inorganic and organic electrophiles. In combination with established Grignard chemistry, new TFVE derivatives 1-3 were obtained from readily available and inexpensive substrates (Figure 6). 

Grignard substitution on allylbromide gave allyl derivative 3 while chlorodimethylvinylsilane and methylacetate gave olefin intermediates 1-2 via substitution with the aryllithium derivative. Formation of bis-TFVE olefin 2 is illustrative of the pronounced reactivity of TFVE-Li toward organic electrophiles. Addition of methyl acetate to a solution of TFVE-Li, followed by protonation, yields the tertiary alcohol [p-F2C=CFOC6H4]2C(CH3)OH, which undergoes rapid dehydration to afford the bis-TFVE olefin 2. Isolated yields of 1-3 after short path... 

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