Abstract: Three acetylenic retinals bearing a triple bond between the carbon atoms 7 and 8, and carrying no, two, or three methyl groups on the cyclohexene ring, were synthesized and various isomers obtained by illumination and subsequent chromatographic separation. The introduction of the acetylenic bond leads to a different geometrical arrangement of the cyclohexene ring with respect to the polyene side chain. Attempts to reconstitute ...
