Dynamic NMR studies of N-benzoyl pyrrolidine and N-benzoyl piperidine derivatives

Consecutive Three‐Component Coupling‐Addition Synthesis of β‐Amino Enoates and 3‐Hydroxypyrazoles via Ethyl 3‐Arylpropiolates

“…Therefore, an orthogonal arrangement of the aryl substituent with the β‐amino enoate indicates that the coalescence phenomenon reflects the rotational barrier of pyrrolidinyl ring. These findings are in good agreement with calculations of pyrrolidine derivatives, such as a 13 C NMR study of N ‐nitrosopyrrolidine, the coalescence temperature of a rigid pyrrolidine enoate and dynamic NMR studies of three N ‐benzoyl pyrrolidines …”

Spectroscopic analysis of imidazolidines Part V: 1H and 13C NMR spectroscopy and conformational analysis of N-acylimidazolidines

“…Compound R NMR spectroscopic methods have been successfully used for obtaining information about the stereochemistry of amides. 5,6 In line with our previous studies related to spectral and biological properties of imidazolidines, [1][2][3][4] we prepared a series of 1-acyl-3-arylimidazolidines 11 (heterocyclic tertiary amides). Because the complete knowledge of structure, including stereochemistry, is essential for lead optimization in drugs discovery, we report herein our studies concerning the structural features of several of those compounds (1-15) ( Table 1) as studied by NMR spectroscopy.…”

“…1 In order to elucidate structure-activity correlations, the study of their conformational features, specially the substituent orientation in molecules of biological interest, has been the object of several investigations. Our laboratory has used 1 H-and 13 C-NMR spectroscopy to study the conformational characteristics of imidazolidines having different substitution patterns (alkyl or aryl groups) at 2,3 Electron delocalization originating from the contribution of structure II (Figure 1) gives partial double-bond character to the N-CO amide bond in its ground state, with rotational barriers in the 15-23 kcal/mol range, [5][6][7][8][9] causing the geometric and magnetic non-equivalence of the nitrogen substituents when R . [5][6][7][8][9] In particular, the E/Z equilibrium in heterocyclic tertiary amides and related compounds has been reviewed.…”

Long-range anisotropic effects in a V–shaped Tröger's base diformanilide: Conformational study by NMR assignment and DFT calculations

“…Slow rotation around the N-C(O) bond and interconversion of conformers is confirmed by 2D EXSY spectra, as a cross peak with opposite phase to NOE correlations is observed for several protons from and close to E and Z formamides. These signals show magnetization transfer between two sites that undergo chemical exchange, and indicate that conversion between the different conformers is in fast exchange on the relaxation time scale, even when it is in the slow exchange limit on the NMR chemical shift time scale [26].…”