Synthesis of (+)-(4S)- and (-)-(4R)-(11Z)-4-hydroxyretinals and determination of the absolute stereochemistry of a visual pigment chromophore in the firefly squid, Watasenia scintillans

Article abstract of DOI:10.1021/jo00102a014

First syntheses of (+)-(4S)- and (-)-(4R)-(11Z)-4-hydroxyretinals (4-OH-RALs) (4a and 4b) were accomplished from (4S)- and (4R)-4-hydroxy-β-ionones, respectively, to determine the absolute configuration of a visual pigment chromophore in Watasenia scintillans, which has been isolated as a new chromophore in the animal kingdom. The CD spectra of the native chromophore and its anti-oxime agreed with those of synthetic (4R)-compounds. Application of the CD exciton chirality method to the p-(dimethylamino)cinnamate of (4R)-4-OH-RAL also established the absolute configuration of the native chromophore as 4b.