Palytoxin,the chapter-opening molecule, is a potent poison first isolated from marine soft...

Palytoxin,the chapter-opening molecule, is a potent poison first isolated from marine soft corals obtained from a tidal pool on the Hawaiian island of Maui.

a.  Ignoring the OH group in blue, label all 2° OH groups that are located on stereogenic centers in palytoxin.

b.  The OH group in blue is part of a hemiacetal, a functional group that has the general structure R2C(OH)OR'; that is, a hemiacetal contains a hydroxyl (OH) and alkoxy group (OR) bonded to the same carbon. Draw the carbocation that results from protonalion and loss of H2O from a hemiacetal. Explain why hemiacetals are more reactive than other 2° alcohols towards loss of H2O in the presence of acid. We discuss hemiacetals in greater detail in Chapter 21.