A convenient synthesis of 3, 4-didehydroretinal was developed. The Horner–Emmons reaction between 3, 4-didehydro-β-ionone and diphenyl phosphonate in the presence of crown ether gave the retinonitrile as an isomeric mixture, in which the newly produced double bond was predominantly 11Z-form. After separation of the 11Z-form retinonitrile, it was converted into the corresponding retinal in good yield without isomerization of the ...
