Vitamin A: Hoffmann-La-Roche synthesis

C.14-C6-Linkage by ethynylation

By ethynylation of the C14-Aldehyde with theC6- The basic carbon structure of vitamin A is built up. The magnesium compound must be freshly prepared from the corresponding alcohol before the reaction, since it cannot be stored indefinitely. The C14-Aldehyde is added dropwise at 0° C in ether and heated 2.5 H long. The desired C.20-Bisalcohol is released from the magnesium alcoholate by hydrolysis with aqueous ammonium chloride solution. For purification, extraction is carried out with 75% aqueous methanol from petroleum ether. The by-products (especially products of elimination of the alcohol functions) remain in the petroleum ether. The yield based on the aldehyde is 81%.

Video: Vitamin - A. structure. synthesis. biosynthesis from MVA (January 2022).