Synthesis and crystal structure of a bench-stable pyridinium ketene hemiaminal: 1-(1-eth-oxy-ethen-yl)-2-[meth-yl(phen-yl)amino]-pyridin-1-ium tri-fluoro-methane-sulfonate

Abstract

The novel bench-stable N-quaternized ketene N,O-acetal, C₁₆H₁₉N₂O⁺·CF₃O₃S^-, was synthesized and its structure determined. The title compound is a rare example of a pyridinium ketene hemiaminal for which a crystal structure has been determined, joining the 2-chloro-1-(1-ethyoxyethen-yl)pyridin-1-ium tri-fluoro-methane-sulfonate salt from which it was synthesized. The cationic species of the title compound can be defined by three individually planar fragments assembling into a non-coplanar cation. The phenyl substituent extending from the amino nitro-gen atom and the ethyoxyvinyl substituent extending from the pyridine N atom are oriented on the same side of the mol-ecule and maintain the closest coplanar relationship of the three fragments. Supra-molecular inter-actions are dominated by C-H⋯O inter-actions from the cation to the SO₃ side of the tri-fluoro-methane-sulfonate anion, forming a two-dimensional substructure.

Keywords: N-quaternized ketene N,O-acetal; crystal structure; ketene hemiaminal.