N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
197 197
Effect of Substituents on the 1 H Chemical Shifts of Monosubstituted Pyrroles
(in ppm)
δ H-1 ≈ 8, broad, solvent-dependent
δ H-2 = 6.71 + Z i2
δ H-3 = 6.23 + Z i3
δ H-4 = 6.23 + Z i4
δ H-5 = 6.71 + Z i5
N
H
2
1
3
5
4
H 3
H 4
Substituent in position 1
Z 12
Z 15
Z 13
Z 14
–CH 3
-0.13 -0.11
–CH 2 CH 3
-0.16 -0.12
–CH 2 CH 2 CN
-0.05 -0.07
–CH 2 –phenyl
-0.12 -0.04
–phenyl
0.36 0.11
–N(CH 3 ) 2
0.11 -0.19
–COCH 3
0.56 0.12
–CO–phenyl
0.57 0.18
–Si(CH(CH 3 ) 2 ) 3
0.08 0.08
H 3
H 4
H 5
H 2
H 4
H 5
Substituent
in position 2 or 5
in position 3 or 4
Z 23
Z 54
Z 24
Z 53
Z 25
Z 52
Z 32
Z 45
Z 34
Z 43
Z 35
Z 42
–CH 3
5.72 5.89 6.36
-0.33 -0.16 -0.26
–NO 2
7.11 6.29 7.05
1.06 0.24 0.43
–C– – – N
6.88 6.28 7.13
0.83 0.23 0.51
–SCH 3
6.23 6.10 6.72
0.18 0.05 0.10
–SCN
6.53 6.15 6.90
0.48 0.10 0.28
–CHO
7.01 6.34 7.18
0.78 0.11 0.47
–COCH 3
6.93 6.26 7.06
0.70 0.03 0.35
–COOCH 3
6.84 6.18 6.91
0.79 0.13 0.29
C
N
S
O
||
C
5.6 Heteroaromatic Compounds