Synthesis and structural study on α-substituted-1-styrylpyridinium salts. Reinvestigation of krohnke condensation

摘要

Kröhnke condensation of several cycloimmonium salts with p-dimethylaminobenzaldhyde has been studied. X-Ray diffraction, IR and Raman spectra, 1H-and 13C-NMR and UV spectra of the products are discussed, being compared, when necessary, with the starting pyridinium salts. All compounds showed the Z configuration, corresponding to the more stable structure, except one, in which steric factors were predominant.