Organic Chemistry of Drug Synthesis. Volume 7

treated with thiazolidinedione proper ( 153 ) in the presence of base. The
anion from the methylene group in 153 adds to the aldehyde; the transient
alcohol dehydrates to form the observed product 154. Catalytic hydrogen-
ation of that product then affordsrivoglitazone( 155 ).^21

N

CH 3 O N

CH 3

OH

150

+

F CH=O NaH

N

CH 3 O N

CH 3

152

O CH=O

151

NH

S

O O

NH

S

O O

153

N

CH 3 O N

CH 3

154

H 2 O

NH

S

N O O

CH 3 O N

CH 3

155

O

Purines in which the sugar moiety is replaced by an abbreviated open-
chain surrogate, for example, acyclovir, comprise an important group of
antiviral drugs. Antiviral activity is retained when the pyrimidine ring in

N

NH

Cl

Cl

Br +

O

AcO OAc

OAc

AcO N

N

Cl

Cl

Br

O

AcO OAc

OAc

H 2 N

N

N

Cl

Cl

O

AcO OAc

OAc

N

N

Cl

Cl

O

HO OH

OH

NH NH

cat

[OH--]

(^156157)
158
160 159

2. FIVE-MEMBERED RINGS WITH TWO HETEROCYCLIC ATOMS 157