Summary With regard to the investigation of the biosynthesis of the C30-carotenoids in citrus fruits apocarotenoids with a methyl group shifted by one position (diapocarotenoids) were synthesized. Characteristical differences, especially in the 270-MHz-'H-NMR. spectra between the apo-and the diapocarotenoids are reported. The comparison of the natural pigments with the synthetic compounds proves that the natural products belong to the ...