TITLE:
Computational Study for the Aromatic Nucleophilic Substitution Reaction on 1-Dimethylamino-2,4-bis(trifluoroacetyl)-naphthalene with Amines
AUTHORS:
Norio Ota, Tomohiro Nakada, Takumi Shintani, Yasuhiro Kamitori, Etsuji Okada
KEYWORDS:
1-Amino-2, 4-bis(trifluoroacetyl)naphthalenes, Aliphatic Amines, Meisenheimer Complexes, Aromatic Nucleophilic Substitution, DFT Calculation
JOURNAL NAME:
International Journal of Organic Chemistry,
Vol.8 No.3,
August
2,
2018
ABSTRACT: Our previous research
showed that aliphatic amines were put in order of high reactivity as “ethylamine
> ammonia > t-butylamine >
diethylamine” on the aromatic nucleophilic substitution of 1-dimetylamino-2,4-bis(trifluoroacetyl)-naphthalene 1 in
acetonitrile. The DFT calculation study (B3LYP/6-31G* with solvation model) for
the reactions of 1 with above four amines rationally explained the difference
of each amines reactivity based on the energies of their Meisenheimer complexes 3 which are assumed to formed as the reaction intermediates in the
course of the reaction giving the corresponding N-N exchange products 2. Intramolecular hydrogen bond
between amino proton in 1-amino group and carbonyl oxygen in 2-trifluoroacetyl
group stabilizes Meisenheimer complexes 3 effectively, and accelerates
the substitution reaction from 1 to 2. Our calculation results
also predicted that the above order of amines is also true if less polar
toluene is used as a solvent instead of acetonitrile even though more enhanced
conditions are required.