Total synthesis of lycopene

A novel route to the total synthesis of lycopene was described. The synthesis was based on the following three steps: (i)the aldol condensation between 4, 8-dimethylnona-3, 7-dienal( 2 )and propionaldehyde( 3 )led to the key intermediate, 2, 6, 10-trimethylundeca-2, 5, 9-trienal( 4 ); (ii)3, 7, 11-trimethyldodeca-1, 3, 6, 10-tetraenylphosphonate( 6 )could be prepared via the modified Wittig-Horner reaction between (4) and methylenebisphosphonic acid tetraethyl ester( 5 ); (iii)another modified Wittig-Horner reaction between( 6 )and C10-triene dialdehyde( 7 )could produce all-E-lycopene( 1 ). The overall yield was 58. 7%. This approach offers many advantages including less steps, simple operations, high-yielding compared with the conventional synthetic routes, and exhibits a potential for large-scale production.