Systematic studies of the alkylation of a number of ambident or ambifunctional anions have been reported. For the vast majority of the anions examined reaction involved competition between carbon and a heteroatom and few competition between two heteroatoms. A study of the factors influencing the site of alkylation of the ambident anion of mono-N-substituted amides, where competition is between oxygen and nitrogen, has been undertaken. With the alkali metal and tetraalkylammonium salts of formanilide anions, the alkylation product is invariably the corresponding N-alkylformanilide. No detectable O-alkylation is observed as the solvent is varied from nonpolar through polar aprotic solvents, the alkylating agent through the various benzyl halides and para-substituted benzyl halides and the para-substituent on the formanilide from strongly electron donating (—OCH3) through strongly electron withdrawing (—NO2) groups. In contrast, with the silver formanilide salts, O-alkylation predominates but here the O:N alkylation ratio varies with the parameters examined. A rationale based on thermodynamic υs. kinetic control and reaction of dissociated υs. undissociated anion is presented to predict the site of reaction in these and other ambident systems.
Die vielstündige‐mehrtägige Alkylierung der Alkalimetall‐ oder Tetraäthylammoniumsalze der Anilide (II) z.B. mit Benzylbromid ergibt in DMF ausschließlich die N‐ 1A alkylierten Produkte (I).
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