¹H,¹³C,¹⁵N, 2D and variable temperature NMR study of the role of hydrogen bonding in the structure and conformation of oxamide derivatives

Abstract

The structure and conformation of N,N'-bis[(2-hydroxy)phenyl]oxamide (1 ); N,N'-bis[(2-methoxy)phenylloxamide (2); NN-bis(pheny1)oxamide (3); N,N'-bis[(l R,2S)-( -)-norephedrineloxamide (4); N,N'-bis[ (1 R,2R)-( -)-norpseudoephedrine]oxamide ( 5 ) ; N-[(2-hydroxy)phenyl]methylamide (6); N-[ (2-methoxy)phenyl]methylamide (7); N-phenylmethylamide (8); N-[ ( -) -norephedrine1methylamide ( 9 ) and N-[( -) -norpseudoephedrine]methylamide (1 0) were unambiguously established by 'H, 13C, 15N, 2 0 and variable temperature NMR spectroscopy. A careful NMR investigation of the conformational behaviour in these systems was relevant. It has been found that the dicarbonylic group in compounds 1-5 has a trans geometry, stabilized by intramolecular hydrogen bonding and that they possess a C2 axis. Compounds 1 and 2 are planar and compounds 1,2,4 and 5 present the amidic proton coordinated by two oxygen atoms.

New 3,3′[2,2′-oxy-bis-(oxazaborolidine)]-ethylenes. Structural studies by NMR, X-ray, and quantum chemistry methods

“…Compounds 3a,b were synthesized by the procedure described previously [9,10]. The reduction of 3a or 3b with BH 3 -THF, followed by the partial hydrolysis of the bis-(1,3,2-oxazaborolidine) containing the B H bond, yielded the tricyclic 2,2 -oxybis-(1,3,2-oxazaborolidines) 4a or 4b, respectively (Scheme 2).…”

“…The syn-FIGURE 1 ORTEP representation of compound 4a. thesis of N,N (hydroxyalkyl)oxamides was accomplished according to the reported procedures [9,10]. 1 H, 11 B, and 13 C NMR spectra were recorded on a JEOL GXS 270 spectrometer.…”

New dithiazinanes and bis‐dithiazinanes‐bearing pendant ethylamines: Structure and reactivity

“…ppm/K belongs to N H solvent associated or having intermolecular bonds. [21][22][23][24][25][26]. Our experiments indicate that compounds 9 (2.1 × 10 −3 ppm/K) and 10 (0.8 × 10 −3 ppm/K) have strong intramolecular bonds, whereas compound 6 (4.0 × 10 −3 ppm/K) has a weaker hydrogen bond.…”

Hydrogen bond studies in substituted N-(2-hydroxyphenyl)-2-[(4-methylbenzenesulfonyl)amino]acetamides

“…This fact confirms that, in DMSO-d6 solution, 7-9, 12 do not have the same hydrogen bonding arrangement than 10 and 11. Chemical shifts for H6 in 8-12 showed that this atom has intramolecular interactions with O2 14 . Thereby, in compounds 10-11 the intramolecular interactions H6•••O2•••H10 are present, where O2 acts a pivot of a pseudobicyclic system.…”