A novel route for the total synthesis of ε-carotene is described. The synthesis is based on a condensation between α-cyclocitral and diethyl [(2E)-3-methoxy-2-methylprop-2-en-1-yl]phosphonate to give a C14 enol ether, hydrolysis of the C14-enol ether to a give a C14 aldehyde, and a modified Wittig–Horner reaction of the C15 phosphonate from the C14 aldehyde and a C10 triene dialdehyde to give ε-carotene. The synthetic steps are easily performed and are practical for large-scale production.
Key words
total synthesis - Wittig reactions - carotenes - isomerizations
