Chapter 18, Problem 1LGP

$\beta$ -Carotene is a highly conjugated hydrocarbon with an orange-red color. Its biosynthesis occurs via the isoprene pathway (Special Topic G in WileyPLUS), and it is found in, among other sources, pumpkins. One of the chemical syntheses of $\beta$ -carotene was accomplished near the turn of the twentieth century by W. Ipatiew (Ber. 1901, 34, 594–596). The first few steps of this synthesis involve chemistry that should be familiar to you. Write mechanisms for all of the reactions from compounds 2 to 5, and from 8 to 9 and 10.