Preparation of (7Z) - and (7Z,11Z) - Vitamin A

Article abstract of DOI:10.1016/S0040-4039(00)79878-9

An efficient access to (7Z)- and (7Z,11Z)-vitamin A is described. Following the addition of a C₆-acetylenic building block to 2,6,6-trimethylcyclohexanone (2), dehydration of the tert. alcohol 3 and formation of the C₁₅-Wittig salt, the (7Z)-geometry was introduced by partial hydrogenation of the triple bond over Raney-nickel. Following Wittig reaction with (E)-2-methyl-4-acetoxy-2-butenal gave a mixture of the title compounds 8 and 9 which could easily be separated.