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752 CHAPTER 19 
 
With the functional group installed, we must now bridge 
the gap between the first and last steps of the synthesis: 
 
 
 
This transformation does not involve a change in the 
carbon skeleton, but it does involve a change in both the 
location and the identity of the functional group. This 
can be achieved in just a few steps: 
 
1) elimination to give an alkene (upon treatment with 
a strong base), 
2) hydroboration-oxidation to convert the alkene into a 
secondary alcohol via anti-Markovnikov addition of 
H and OH, and 
3) oxidation of the secondary alcohol to a ketone (with 
chromic acid). 
The entire synthesis is summarized here: 
 
 
 
 
 
(f) This transformation does not involve a change in the 
carbon skeleton, but it does involve a change in both the 
location and the identity of the functional group: 
 
 
 
This can be achieved in just a few steps: 
1) elimination with a strong, sterically hindered base 
to give the less substituted alkene, 
2) hydroboration-oxidation to convert the alkene into a 
primary alcohol via anti-Markovnikov addition of H 
and OH, and 
3) oxidation of the primary alcohol to an aldehyde 
(with PCC or DMP or Swern): 
 
 
 
 
(g) The product is an enamine, which can be prepared 
from the corresponding ketone: 
 
 
This ketone can be made from benzene via a Friedel-
Crafts acylation: 
 
 
 
(h) The desired product is an acetal, because the 
following (highlighted) carbon atom is connected to two 
oxygen atoms: 
 
 
Therefore, this acetal can be made (via acetal formation) 
from the following diol and formaldehyde, as shown: 
 
 
 
So we will need to make this diol from the starting 
material. This can be achieved in just two steps. First, 
the starting diyne is treated with sulfuric acid, in the 
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