1 (461)

Prévia do material em texto

CHAPTER 13 453 
 
 
13.15. 
(a) The allylic hydroxyl group appears in the upper right 
corner, so a Sharpless epoxidation with (+)-DET will 
generate an epoxide ring above the plane of the  bond, 
giving the following enantiomer. 
 
 
 
(b) We begin by redrawing the compound so that the 
allylic hydroxyl group appears in the upper right corner. 
A Sharpless epoxidation with ()-DET will generate an 
epoxide ring below the plane of the  bond, giving the 
following enantiomer. 
 
(c) We begin by redrawing the compound so that the 
allylic hydroxyl group appears in the upper right corner. 
A Sharpless epoxidation with (+)-DET will generate an 
epoxide ring above the plane of the  bond, giving the 
following enantiomer. 
 
 
(d) We begin by redrawing the compound so that the 
allylic hydroxyl group appears in the upper right corner. 
A Sharpless epoxidation with ()-DET will generate an 
epoxide ring below the plane of the  bond, giving the 
following enantiomer. 
 
 
13.16. 
(a) The Grignard reagent (PhMgBr) is a strong 
nucleophile, and it attacks the epoxide at the less 
substituted position. The epoxide is opened, resulting in 
an alkoxide ion. This alkoxide is then protonated upon 
treatment with water. 
 
 
 
(b) Cyanide (NC‾) is a good nucleophile, and it attacks 
the epoxide at the less substituted position. This opens 
the epoxide, resulting in an alkoxide ion, which is then 
protonated upon treatment with water. 
 
 
 
(c) MeS‾ is a very strong nucleophile, and it attacks the 
epoxide at the less substituted position. This opens the 
epoxide, resulting in an alkoxide ion, which is then 
protonated upon treatment with water. 
 
 
 
(d) LiAlH4 is a source of nucleophilic hydride (H‾), and 
it attacks the epoxide at the less substituted position. 
This opens the epoxide, resulting in an alkoxide ion, 
which is then protonated upon treatment with water. 
 
 
www.MyEbookNiche.eCrater.com