Basicity of the polydentate captodative aminoenones. Ab initio , DFT, and FTIR study

Abstract

Electron donating ability of the oxygen, nitrogen, and carbon atoms of captodative aminoenones R'CH = C(NR 2 )EWG, EWG = CHO, C(O)Me, C(O)CF 3 , C(O)Ph was investigated using ab initio and Density Functional Theory (DFT) calculations, Natural Bond Orbital (NBO) analysis, and Fourier Transform InfraRed (FTIR) spectroscopy. The influence of both electron withdrawing group (EWG) and double bond substituents on the proton affinity of the basic centers, orbital interaction, as well as resonance stabilization energies between heteroatoms and double bonds are discussed. The results obtained are critically compared with the pushpull aminoenones. The comparison of experimental values ΔνOH and theoretical values of H-bonding energy was used to determine the H-complex type of aminoenone with phenol and the H-bond strength. a Current work. Chart 3. Unusual reactions of captodative aminoalkenes. BASICITY OF THE CAPTODATIVE AMINOENONES. AB INITIO, DFT, AND FTIR STUDY a PA are ΔH 298 values. b PCM calculations in CCl 4 (ε = 2.23) (italic). c PCM calculations in water (ε = 78.36) (bold). BASICITY OF THE CAPTODATIVE AMINOENONES. AB INITIO, DFT, AND FTIR STUDY

The Bonding Interactions in Fluorinated Vinylogous Amides: A CF3‐Substituted Carbonyl‐β‐Aminoenone as a Case Study

“…[ 1 ] Aminoenones are widely used for the synthesis of heterocycles bioactive and analogs of naturally occurring compounds. [ 1,2 ]…”

“…When an electron withdrawing group (EWG) in the α‐carbon atom of the olefin like trifluoromethyl is taken into account, the compound becomes a “capto‐dative olefin”. [ 1,2 ] Both properties in the same unit reveal a molecule with a varied and high chemical reactivity. The particular properties of the fluorine atom, such as strong electronegativity, small size and the low polarizability of the C─F bond, impact on the behavior of a molecule in a biological environment, being the H/F interchange one of the most employed monovalent isosteric replacements in drug design.…”

“…The main conformation and isomeric forms are depicted in Scheme using the s‐ cis /s‐ trans designation, applied in dienes to describe the orientation of both unsaturated bonds with respect to the intermediate single “s” bond, adopted for enamine systems. [ 2,13 ] For the present example the cis / trans terminology is not strictly correct, since there are no two equal groups (or hydrogen) around the single bond used as reference. In related trifluoromethyl N,N ‐disubstituted aminoenones, the calculated energy difference between the E, s‐ cis and E, s‐ trans structures is less than 2 kcal/mol.…”

“…In related trifluoromethyl N,N ‐disubstituted aminoenones, the calculated energy difference between the E, s‐ cis and E, s‐ trans structures is less than 2 kcal/mol. [ 2 ] Although the most stable conformation in “push–pull” aminoenones without hydrogen atom at the amino group is the E, s‐cis , [ 2,13 ] the presence of an acidic hydrogen (N‐H or NH 2 ) strongly shifts the equilibria between both species to the Z, s‐ cis isomer. This class of compounds are present as individual anancomers as established in closely related compounds.…”