The possible role of conformational isomerism in the biological actions of acetylcholine: spectral studies

Abstract

Infrared studies of the NC‐H stretching frequencies of selected trimethylammonium salts, including acetylcholine, were made in an attempt to obtain evidence that intramolecular NC‐H—O hydrogen bonding is responsible for the existence in solution of a quasi‐ring conformation for acetylcholine. Acetylcholine and related compounds were also examined by nuclear magnetic resonance spectroscopy. The carbonyl stretching frequencies of an homologous series of acetoxy alkyl sulphones were measured in dioxan solution to gain information on the effect of electron withdrawing substituents in the absence of intermolecular hydrogen bonding. The observed high ester carbonyl absorption frequency in acetylcholine may be interpreted in terms of the inductive effect from the onium nitrogen atom but the results are not incompatible with the existence of a quasi‐ring conformation involving C‐H—O hydrogen bonding between one of the N‐methyl groups and the acetoxy oxygen atom.

Conformations of erythro- and threo-Dimethylacetylcholine Iodides in the Solid State

“…The latter type of "hydrogen bonds" have been implied as stabilizing factors for ACh molecules in both the solid state and solution (6,12). The latter type of "hydrogen bonds" have been implied as stabilizing factors for ACh molecules in both the solid state and solution (6,12).…”

Conformation of Some Acetylcholine Analogs as Solutes in Deuterium Oxide and Other Solvents

“…If the positive charge on the onium function is distributed around the periphery of the group (24), the interaction might be represented more correctly by NC-H---0, as proposed earlier (5), even though there is no precedent or evidence for the existence of formal hydrogen bonds of this nature (27,28). The additional IR and PMR studies of Ach and its N-substituent congeners uphold the preferred nature of the gauche +N/O conformers of the parent compound in deuterium oxide and, by analogy, in water.…”

2,3-Disubstituted 1,6-naphthyridines as potential diuretic agents

“…Synthesis.$ 2-Hydroxy-3-cyano-l,6-naphthyiidine (14). A mixture of 2.44 g (0.02 mol) of 4-aminonicotinaldehyde, 4.52 g (0.04 mol) of ethyl cyanoacetate, 0.50 ml (0.005 mol) of piperidine, and 50 ml of absolute EtOH was refluxed together for 1 hr.…”