1 (490)

Prévia do material em texto

482 CHAPTER 13 
 
 
 
 
 
13.67. 
(a) The conversion of 1 to 2 utilizes a Sharpless asymmetric epoxidation, so the product is expected to be an epoxide. 
The stereochemical outcome can be deduced by applying the paradigm provided in Figure 13.3. Since the chiral 
catalyst was formed using (–)-DIPT, which affords the same stereochemical outcome as (–)-DET, we can conclude that 
the epoxide forms “below the plane” of the alkene: 
 
 
 
(b) First consider the reagents. Sodium hydroxide will deprotonate 2-ethoxyphenol to give a phenolate ion. 
 
 
 
The phenolate ion can serve as a nucleophile and attack epoxide 2 in a ring-opening reaction. Nucleophilic attack 
occurs at the benzylic position (the carbon atom attached to the benzene ring) to form an alkoxide intermediate, that is 
protonated to give diol 3. 
 
www.MyEbookNiche.eCrater.com