ChemInform Abstract: Retinoids. Part 9. Regulation of the 6-s Equilibrium Conformation of Retinal in Bacteriorhodopsin by Substitution at C-5; 5-Methoxy- and 5-Ethylretinalbacteriorhodopsin.

ChemInform Abstract

5-Methoxyretinal (IXa) is prepared from the ester (I) via threefold chain elongation. Whereas the Wittig-Horner reaction of (V) produces the C15-aldehyde (VII) exclusively as the β-isomer, the labile title compound (IXa) is obtained together with its α-isomer (X). The synthesis of 5-ethylretinal (IXb) is known. The steric and electronic influences of the title compounds on the UV spectra of the corresponding bacteriorhodopsins are investigated.