Am1 Electron-Density And Nmr Spectral Studies Of Carotenoids With A Strong Terminal Electron-Acceptor

NMR spectral analyses of 7',7'-dicyano-7'-apo-beta-carotene (1), which was synthesized to assess the effect of a terminal strong electron acceptor on the structure of carotenoids and the molecular features which control their photochemical properties, are presented. AM1 Molecular orbital calculated electron density differences for 1 and 8'-apo-beta-caroten-8'-al (2)have been found to correlate with the differences in C-13 NMR chemical shifts using beta-carotene (3) as a reference.