Chapter 13.12, Problem 25ATS

A key step in the synthesis of β-vetivone, a major constituent of vetiver, a perennial grass found in tropical and subtropical regions of the world, involved the reaction of compound A and dihalide B with two equivalents of LDA to form C. Draw a stepwise mechanism for this reaction. β-Vetivone contains a spiro ring system—that is, two rings that share a single carbon atom.

Explain the following reaction with a mechanism.

It is often helpful to have more than one way to make a given molecule, as you may not know ahead of time which strategy will be more successful.... 4-Hexyne-2-ol can be made from propene in two different ways – one by way of a bromohydrin, using a protecting group strategy, and another by using an epoxide (which does not need a protecting group strategy). (a) First, give the synthesis which goes through the bromohydrin and uses a protecting group. OH (b) Now, modify the synthesis (you may start with propene, or any other molecule you already made in part (a)) to accomplish the synthesis of 4-hexyne-2-ol using an epoxide.