An efficient modular synthesis of conjugated omega-(p-hexyloxyphenyl)polyenals

Convenient precursors (alpha,beta -unsaturated aldehydes 1-5) for all-E con jugated omega-(p-hexyloxyphenyl)polyenals having two (15), four (16), five, (19), six (17) and eight (18) conjugated double bonds were synthesized in a modular synthesis using reactive silyl enol ethers [1-(trimethylsilyloxy) -1,3-butadiene or 1-(trimethylsilyloxy)-1,3,5-hexatriene)] as building bloc ks, and 5,5-diethoxypenta-2-enal (1) as a template. Polyene 8 containing th ree conjugated double bonds in its structure was obtained from omega-(p-hex yloxyphenyl)propenal (6) and butadienyl ethyl ether as starting materials.