Chemistry Reference
In-Depth Information
The combination of these compounds will generate the target compound through a
four-step synthetic sequence. The first step, illustrated below, is a Wittig reaction
between cyclohexylidine triphenylphosphorane and 3-bromo-4-acetoxycyclohexa-
none. The mechanism for the Wittig reaction was presented in Problem 2(a) of this
chapter.
The second step of this sequence is an E2 elimination reaction generating a diene.
The mechanism for an E2 elimination was presented in detail in Chapter 6. For this
reaction to proceed, it is important to chose a base that is not nucleophilic and
strong enough to remove an allylic proton. Lithium diisopropylamide is generally
sufficient to affect this transformation.
The third step of this sequence, illustrated below, is an ester hydrolysis reaction.
The mechanism for a base-mediated ester hydrolysis was highlighted in
Scheme 7.19.
The fourth and final step of this sequence, illustrated below, is an oxidation of an
alcohol to a ketone. This transformation can be accomplished utilizing the Swern
oxidation. The mechanism for the Swern oxidation is shown in Problem 3(d) of
this chapter.
