O
anion
exchange
resin
NO2
NO2
HO
NMeR
+
RNHMe/EtOH
Me
+
N
Me
N
Me
N
N
Me
_
_
Me
Me
Me
ClO4
Me
ClO4
15
14
16a,b
16 a R = H, b R = Me
Data of elemental analysis and spectral characteristics are given in Tables 1–7 for compounds synthe-
sized for the first time.
We have therefore established the principal difference in the behavior of quaternary 3-, 4-, and 5-nitro-
pyridinium salts under the action of bases. A nitro group in positions 3 and 5 of the nucleus of the pyridinium
salt activates addition of nucleophile at positions 2 and 6 of the nucleus, accompanied by recyclization, but the
nitro group in position 4 of the nucleus directs attack of the nucleophile to position 4, which leads to
nucleophilic ipso substitution of the nitro group.
1
TABLE 3. H NMR Spectra of Pyridinium Salts
Chemical shifts, δ, ppm (J, Hz)*
Compound
N–CH3
Other protons
(s)
1a
1b
1c
3
4.44
4.44
4.39
4.34
2.75 (3H, s, COCH3); 2.86 (3H, s, 2-CH3); 9.52 (1H, d, 4J = 2.4, H-4);
10.21 (1H, d, 4J = 2.4, H-6)
1.27–1.35 (4H, m, 2CH2); 2.57–2.88 (1H, m, CH); 2.88 (3H, s, 2-CH3);
9.43 (1H, d, 4J = 2.2, H-4); 10.22 (1H, d, 4J = 2.2, H-6)
2.73 (3H, s, 2-CH3); 7.61–7.90 (5H, m, C6H5); 9.12 (1H, d, 4J = 2.2, H-4);
9.68 (1H, d, 4J = 2.2, H-6)
5.22 (2Н, s, СН2); 7.58–7.73 (3H, m, C6H5); 8.08–8.13 (2H, m, C6 H5);
8.24 (1Н, d, 3J = 8.8, Н-3); 9.14 (1Н, dd, 3J = 8.8, 4J = 2.4, Н-4);
9.69 (1H, d, 4J = 2.4, H-6)
6
4.54
4.15
4.21
4.21
7.53–7.72 (3H, m, C6H5); 7.83–7.88 (2H, m, C6H5); 8.39 (1Н, d, 3J = 8.8,
Н-3); 9.10 (1Н, dd, 3J = 8.8, 4J = 1.8, Н-4); 9.65 (1H, d, 4J = 1.8, H-6)
7
2.88 (3Н, s, 6-CH3); 2.91 (3Н, s, 2-CH3); 8.15 (1Н, d, 3J = 8.7, H-5);
8.96 (1Н, d, 3J = 8.7, H-4)
10a
10b
2.71 (3H, s, COCH3); 2.88 (3H, s, 2-CH3); 2.93 (3H, s, 6-CH3); 9.31
(1H, s, H-4)
1.23–1.37 (4H, m, 2СН2); 2.53–2.62 (1H, m, CH); 2.89 (3H, s, 2-CH3);
2.94 (3H, s, 6-CH3); 9.23 (1H, s, H-4)
10c
10d
4.26
4.24
3.00 (6H, s, 2,6-CH3); 9.28 (1H, s, H-4)
2.73 (3H, s, 2-CH3); 2.99 (3H, s, 6-CH3); 7.61–7.68 (2H, m, C6H5);
7.80–7.87 (3H, m, C6H5); 9.20 (1H, s, H-4)
14
3.97
3.78
2.60 (3Н, s, 2-CH3); 7.12 (1Н, dd, 3J = 7.1, 4J = 2.9, H-5); 7.19 (1Н, d,
4J = 2.9, Н-3); 8.55 (1H, d, 3J = 7.1, H-6)
16a
2.51 (3Н, s, 2-CH3); 2.86 (3Н, d, J = 5.0, NHCH3); 6.76 (1Н, dd,
3J = 7.2, 4J = 2.8, H-5); 6.82 (1H, d, 4J = 2.8, H-3); 8.24 (1Н, d, 3J = 7.2,
Н-6); 8.34 (1Н, br. s, NHCH3)
16b
3.83
2.53 (3Н, s, 2-CH3); 3.16 (6Н, s, N(CH3)2); 6.90 (1Н, dd, 3J = 7.8,
4J = 2.4, Н-5); 6.96 (1Н, d, 4J = 2.4, H-3); 8.18 (1H, d, 3J = 7.8, H-6)
_______
*The 1H NMR spectra were taken in DMSO-d6 (compounds 1a–c, 7, 10a,b,d, 14 and 16a,b) and CD3CN (compounds 3, 6, and 10c).
475