¹H‐NMR‐Untersuchungen zur innermolekularen Beweglichkeit substituierter Acrylsäureester

Abstract

1H‐N.M.R. Spectroscopic Investigations on Innermolecular Mobility of Substituted Acrylates The barriers of rotation around the CC‐bond of, ethyl 3‐arylamino‐2‐nitro‐acrylates 1 and ethyl 3‐arylamino‐2‐cyano‐acrylates 2 have been determined by dynamic n.m.r. spectroscopy. From coalescence phenomena the free activation enthalpies ΔG≠ of rotational processes are determined and discussed with respect to substituent effects.

(Z), Not (E) – An End to a Century of Confusion about the Double‐Bond Stereoisomers of 3‐Amino‐2‐cyanoacrylates

“…For a range of compounds containing enamine moieties, interconversion between diastereomeric forms has been shown to take place in liquid state or solution under different conditions . For these compounds, the ability to rotate around the partial double bond depends on the substituents of the amine and the alkene .…”

“…For a range of compounds containing enamine moieties, interconversion between diastereomeric forms has been shown to take place in liquid state or solution under different conditions. [44][45][46][47][48][49] For these compounds, the ability to rotate around the partial double bond depends on the substituents of the amine [44] and the alkene. [47] A correlation between the ability to form intramolecular hydrogen bonds and the predominance of one isomer has been observed in several studies.…”

“…[44][45][46][47][48][49] For these compounds, the ability to rotate around the partial double bond depends on the substituents of the amine [44] and the alkene. [47] A correlation between the ability to form intramolecular hydrogen bonds and the predominance of one isomer has been observed in several studies. [44][45][46] Introducing further complexity, some compounds even crystallize in only one isomeric form, while an equilibrium between the isomeric forms exists in liquid state or solution, [44] which excludes solid-state methods as a means to determine the stereochemistry of aminocyanoacrylates in solution.…”