Hybrids of Salicylalkylamides and Mannich Bases: Control of the Amide Conformation by Hydrogen Bonding in Solution and in the Solid State

Abstract

3-Aminomethylation of salicylalkylamides afforded hybrids with a Mannich base. In addition, it triggered the rotation of the amide bond. The observed conformational switch is driven by strong intramolecular hydrogen bonding between the Mannich base and phenolic group. Crystal structure analysis reveals the stabilization of the hybrid molecules by double hydrogen bonding of the phenolic OH, which acts as an acceptor and donor simultaneously. The molecules contain an amide site and a Mannich base site in an orthogonal spatial arrangement. The intramolecular hydrogen bonds are persistent in a nonpolar solvent (e.g., chloroform). The conformational change can be reversed upon protection or protonation of the Mannich base nitrogen.

Synthesis, Anti-inflammatory, and Antioxidant Activity of Mannich Bases of Dehydrozingerone Derivatives

“…The data were supported by the disappearance of the broad peak of OH phenolic in the FTIR spectra of the compound because of the formation of intramolecular hydrogen bonding between the OH group and N atom of the Mannich base. [21][22] The structures were further supported by 13 C-NMR spectra which provided the expected number and types carbons of the carbonyl, aromatic, ethylenic and aliphatic moieties of the compounds, and by MS spectra which provided the molecular masses of the compounds. These values are in the complete agreement with the structure assigned.…”

Synthesis and Antioxidant Activity Study of New Mannich Bases Derived From Vanillic Acid

“…The disappearance of a sharp peak of OH phenolic in the infrared spectra of prepared compounds at 3483 cm -1 indicating hydrogen bonding formation between OH and N of the Mannich base. 20 The bands at the range of 1084-1155 cm -1 conform to C-N, C-O phenol, and C-O ether. In the infrared spectra of 2a and 2b were observed the disappearance of the C=O carboxylate peak at 1564-1667 cm -1 indicated the occurrence of decarboxylation.…”

Insight into the broadened substrate scope of nitrile hydratase by static and dynamic structure analysis

“…X-ray diffraction measurements for M46R and A129R were performed on a Bruker D8 VENTURE diffractometer. 39 The diffraction data for M46R and A129R were indexed, integrated, and merged using the Proteum2 software suite. The crystals of M46R and A129R belonged to the same space group as that of wild-type Pt NHase, with nearly identical unit cell dimensions, allowing the wild-type crystal structure (PDB entry ) to be used directly for initial refinement and electron-density map calculations.…”