title: Structure investigations of agonists of the natural neurotransmitter acetylcholine, III. X-ray structure analysis of (2-ethoxyethyl)trimethylammonium chloride.
abstract: To elucidate the structure-activity correlations we have performed an X-ray structure analysis of the title compound (1), which is a muscarinic agonist of the natural neurotransmitter acetylcholine. 1 crystallizes in the monoclinic space group P2(1)/n with 2 molecules per asymmetric unit. Lattice parameters are: a = 10.375(6), b = 12.468(5), c = 15.274(17) A; beta = 95.32(7) degrees. The structure was solved by direct methods and refined to an R-value of 0.14 for 1828 observed reflections. Both cations in the asymmetric unit are disordered. In the crystal structure at least four conformations of the cation occur, indicating a pronounced conformational flexibility of the neurotransmitter cation. The anions are arranged stereospecifically with respect to the quaternary trimethylammonio methyl group. The geometry of triangles which are defined by a nitrogen of the quaternary ammonium group and an ether oxygen on one hand and an anion occupying a specific type of tetrahedral faces of a (CH3)3N+ CH2 group on the other hand, is characteristic for muscarinic agonists if they contain an ether or ester oxygen in the analogous position to the ester oxygen of acetylcholine.
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors*; D002794:Choline / Q000031:analogs & derivatives*; D008958:Models, Molecular; D008968:Molecular Conformation; D018377:Neurotransmitter Agents; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D018377:Neurotransmitter Agents; C027084:O-ethylcholine; D002794:Choline; D000109:Acetylcholine