11-Methyl-9-demethylretinal and 11-Methyl-9,13-didemethylretinal. Effect of Altered Methyl Substitution Pattern on Polyene Conformation, Photoisomerization and Formation of Visual Pigment Analogs

Article abstract of DOI:10.1016/S0040-4020(01)80897-8

Altered methyl substitution in 11-methyl-9-demethylretinal (1) and 11-methyl-9,13-didemethylretinal (2) resulted in changed polyene conformation, regioselectivity of photoisomerization, uv/vis characteristics and reactivity toward bovine opsin.That the 11-cis isomer of 1 and 9-cis isomer of 2 gave visual pigment analogs (λ_max 475 and 459 nm respectively) while the 11-cis isomer of 2 did not is consistent with the requirement of a twisted chromophore near the middle of the polyene chain for pigment formation.