A condensation C15 + C5 between ethynyl-β-ionol and a derivative of prenal was performed at low temperature in the presence of a Lewis acid. The coupling occurs at position 7 of ethynyl-β-ionol and led to the efficient synthesis of a new C20 molecule rather than the expected retinal.
MayerH., and IslerO., Carotenoids, Birkhäuser Verlag, Basel-Stuttgart, 1971.
2.
RandallC.E., LewisJ. W., HugS. J., BjörlingS. C., Eisner-ShanasI., FriedmanN., OttolenghiM., ShevesM., and KligerD. S., J. Am. Chem. Soc., 1991, 113, 3473.
3.
LiuR.S. H., and AsatoA. E., Tetrahedron, 1984, 40, 1931.
4.
JuliaM., and ArnouldD., Bull. Soc. Chem. Fr., 1973, 2, 746. P. Chabardes, J.-P. Decor and J. Varagnat, Tetrahedron, 1977, 33, 2799.
5.
For a similar approach using palladium chemistry see BienayméH., Tetrahedron Lett.1994, 35, 7383.
6.
(a) HennionG. F., and BoisselleA. P., J. Org. Chem., 1961, 26, 725; (b) J. Landor, J. Chem. Soc., Perkin Trans II, 1972, 1995; (c) M. Bourgain-Commerçon, J. F. Normant and J. Villieras, J. Chem. Res. 1977, (S) 183, (M) 2101; (d) H. Mayr and H. Klein, J. Org. Chem., 1981, 46, 4097; (e) K. Ruitenberg, H. Kleijn, H. Westmijze, J. Meijer and P. Vermeer, Recl. Trav. Chim. Pays-Bas, 1982, 101, 405.
