Medicinal Chemistry

22

Classical bioisosteres

1. Monovalent atoms or groups:
   OH
   SH
   Br
   I

NH

PH

-Pr

2

2

i

CH 3 CI F H

CH 2

COCH R 2 CONHR

NH O S

CO R 2 COSR

CH

P

N

As

2. Bivalent atoms or groups:


3. Trivalent atoms:

C Si N+ P+

4. Tetravalent atoms:

Nonclassical bioisosteres

1. Functional group replacements:
   a. Halogens:
   XCF 3 CN N(CN) 2 C(CN) 3
   b. Hydroxyl group:
   OH
   NHCOR

CH OH

NHSO R

2

2

CH(CN)

NHCN

2

NHCONHR

c. Carbonyl group:

C

O

S

O OO

S S

O

NH C

NC CN NOH

C

d. Carboxylic acid group:

(Continued)