A new coumarin analogue of retinal was synthesised by Wittig condensat
ion of (2-oxo-2H-chromen-3-yl)methyltriphenylphosphonium chloride and
(2E,6Z) imethyl-8-triphenylsilyloxyocta-2,6-dien-4-yn-1-al in high yie
ld. Subsequent triphenylsilyl group removal, MnO2 oxidation, followed
by hydrogenation over Lindlar catalyst and isomerization in the presen
ce of traces of iodine furnished the desired polyenal. This ail-trans
coumarin analogue of retinal was used for study of the bacteriorhodops
in chromophore binding site. Copyright (C) 1996 Elsevier Science Ltd