Anions anilinide

Aiyl, 2-lietaryl-, and 2-alkylquinazolin-4(3W)-ones 14 are readily accessible by a novel, general, and effective approach via reaction of lithium 2-[(diethylamino)carbonyl]anilinide with aromatic, heteroaromatic, and aliphatic nitriles. Presumably, Ihe hctcrocyclization reaction proceeds via the intermediacy of species 13 arising from the nucleophilic attack of the preformed anion 12 on the reactive nitrile moiety. 

According to the Brpnsted definition, the acidity of a molecule is associated with its capacity to give up a proton Ph—NH2 — Ph—NH +H+. The change of standard enthalpy or free energy of this deprotonation reaction is a measure of the intrinsic acidity. As discussed above, in solution, the propensity of an aniline derivative is to accept a proton. The measured dissociation constant (pATa) is related to the basicity of the neutral molecule (or the acidity of the anilinium cations). As a consequence, relatively little is known about their acidity and/or the anilinide anions. However, the NH acidities have been well established in hydroxamic acids even though the latter usually behave as O-acids134. It is therefore of interest to get some insight into the deprotonation of aniline in the gas phase. 

The adiabatic ionization energy of the anilinide anion is evaluated to be Ilia(PhNII ) = 1.7 0.1 eV, which is smaller than that of 2.25 eV measured for phenolate anion135. TD-DFT computations suggest that the lowest vertical n +- n excitations of the N-anion are centered at 1.9 eV (1 A") and 2.1 eV (l A"). Thus, its excited valence states are expected to be auto-ionizing. Substitution of the H(N) atom by fluorine increases the anion IE by 0.3 eV, whereas substitution by a methyl group slightly reduces it (0.05 eV). 

As in the case of phenolate anions, it is possible to stabilize anilinide anions by alkali metal cations. Figure 17 displays the selected optimized geometrical parameters of the... 

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