Chinolinanaloge Chalkone: Wittig-Synthese, 13C-NMR-Spektren und Bestimmung von σ-Konstanten für die 2-, 3 und 4-Position des Chinolins

Quinolineanalogous Chalcones: Wittig Synthesis, ¹³C-N.M.R. Spectra and Estimation of σ-Constants for the 2-, 3- and 4-Position of Quinoline The Wittig type reaction of the quinolinealdehydes 2a—c with benzoylmethylentriphenylphosphorane ( 1 ) gives stereoselectively the E-configurated quinolineanalogous chalcones 3a—c . These compounds react with methyl iodide to the N-methyl-quinolinium salts 4a—c . The complete ¹³C-n.m.r. analysis of 3a—c is reported. From the chemical shift of the C_α-signals and on the basis of a Hammett relationship σ-constants were calculated for the 2-, 3- and 4-position of quinoline. These values are compared with those from kinetic measurements; the observed deviations are chiefly attributed to the extent of the resonance interaction in 3a—c .