1
Q
F / Cl / Br/ CH3 / OH/ SH
A
Classical, Univalent
2
Q
H to F
A
Classical, Univalent
3
Q
-O- to a -NH- or to a -CH2 or to a -S-
A
Classical, Divalent
4
Q
-CO2R to a COSR
A
Classical, Divalent
5
Q
C=O, C=S, C=NH
A
Classical, Divalent
6
Q
R-N=R’ or R-CH-R’ or R-P=R
A
Classical, Trivalent
7
Q
R=C=R’ to R=N=R
A
Classical, tetrasubsituteds (least common)
8
Q
Benzene to pyridine to pyrrole to furan to thiophene
A
Classical, ring equivalents
9
Q
Cyclic to acyclic
A
Non-classic
10
Q
Carbonyl to a sulfonyl
A
non-classical
11
Q
Carboxylic acid to a tetrazole
A
non-classical
12
Q
Amides to a sulfonamide
A
non-classical
