Advices For Studying Organic Chemistry

3) Zaragozic acid A (which is also called squalestatin S1 and has been shown to

lower serum cholesterol levels in test animals by inhibition of squalene

biosynthesis) by K. C. Nicolaou (University of California San Diego, Scripps

Research Institute):

Zaragozic acid A O

HO 2 C O

OH CO^2 H

HO 2 C

OCOCH 3

O OH

O

(squalestatin S1)

11.18 REACTIONS OF EPOXIDES

A Mechanism for the Reaction

Acid-Catalyzed Ring Opening of an Epoxide

CC

O O+

+ HOH

H

CC

H

+ OH

H

Epoxide Protonated epoxide

+

The acid reacts with the epoxide to produce a protonated epoxide.

CC

O

O+ H O O

H H

+

Protonated

epoxide

Weak

nucleophile

Protonated

glycol

Glycol

CC

H

+ OH

H

+ OH

H CC

O

H

H

H OH

H

+

The protonated epoxide reacts with the weak nucleophile (water) to form a

protonated glycol, which then transfers a proton to a molecule of water to form the

glycol and a hydronium ion.