PAPER
Ruthenium(II)–Porphyrin Catalyzed Selective N-Imidation of Aromatic Nitrogen Heterocycles
1463
4-(Dimethylamino)pyridinium N-Tosylimide (2)
flow, moderate to high yields, and easy preparation of the
nitrene precursors. The reaction proceeds in a highly se-
lective manner, generating exclusively the products of the
imidation reaction of the sp2 nitrogen.
1H NMR (400 MHz, CDCl3): d = 2.30 (s, 3 H), 3.07 (s, 6 H), 6.44
(d, J = 8.0 Hz, 2 H), 7.09 (d, J = 7.6 Hz, 2 H), 7.53 (d, J = 8.0 Hz, 2
H), 7.69 (d, J = 7.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3): d = 21.0, 39.6, 106.3, 126.6, 126.7,
139.3, 140.6, 144.1, 153.9.
All catalyses were performed under N2 and argon atmosphere. Sili-
ca gel F254 plates were used for TLC and spots were examined un-
der UV light at 254 nm and developed by I2 vapor. Flash
chromatography was performed on silica gel H. Solvents were pu-
HRMS (ESI+): m/z [M + H]+ calcd for C14H18N3O2S: 292.1114;
found: 292.1115.
1-Methyl-1H-benzimidazol-3-ium N-Tosylimide (10)
1H NMR (600 MHz, CDCl3): d = 2.31 (s, 3 H), 4.12 (s, 3 H), 7.07
(d, J = 8.0 Hz, 2 H), 7.27–7.36 (m, 2 H), 7.43–7.49 (m, 2 H), 7.63
(d, J = 8.0 Hz, 2 H), 9.22 (s, 1 H).
13C NMR (150 MHz, CDCl3): d = 21.3, 33.2, 113.2, 114.0, 125.5,
126.1, 126.8, 129.3, 130.7, 132.6, 140.5, 142.1, 142.3.
1
rified according to standard procedures. H and 13C NMR spectra
were recorded on Bruker AC-E 200 MHz Varian Mercury 400 MHz
and Bruker Avance 600 MHz spectrometer, using CDCl3 as the sol-
vent. The mass spectra (ESI/HRMS) were recorded on a Bruker
Daltonics Data analysis 3.2 mass spectrometer.
N-Imidation of Aromatic Nitrogen Heterocycles; Typical Pro-
cedure
HRMS (ESI+): m/z [M + Na]+ calcd for C15H15N3NaO2S: 324.0777;
found: 324.0769.
A reaction flask was charged with substrate (1 mmol), phenyl(to-
sylimino)iodinane (1.5 mmol), catalyst (0.5 mmol%), 4 Å molecu-
lar sieves, and CH2Cl2. The mixture was stirred at 30 °C under an
N2 atmosphere for 2–6 h. After cooling to r.t., the resulting mixture
was filtered; the filtrate was concentrated in vacuo. The residue was
purified by flash column chromatography (silica gel, CH2Cl2–
acetone, 4:1) to afford the product of N-imidation.
1,2-Dimethyl-1H-benzimidazol-3-ium N-Tosylimide (11)
1H NMR (600 MHz, CDCl3): d = 2.34 (s, 3 H), 2.74 (s, 3 H), 3.87
(s, 3 H), 7.08 (d, J = 8.0 Hz, 2 H), 7.09 (d, J = 8.2 Hz, 1 H), 7.15 (td,
J = 1.0, 8.2 Hz, 1 H), 7.35 (td, J = 1.0, 8.2 Hz, 1 H), 7.39 (d, J = 8.2
Hz, 1 H), 7.57 (d, J = 8.0 Hz, 2 H).
13C NMR (150 MHz, CDCl3): d = 10.6, 21.3, 31.6, 110.5, 114.7,
124.9, 125.5, 126.7, 129.0, 129.7, 132.7, 140.8, 142.1, 151.4.
Pyridinium N-Tosylimide (6)
1H NMR (400 MHz, CDCl3): d = 2.36 (s, 3 H), 7.17 (d, J = 8.0 Hz,
2 H), 7.58–7.59 (m, 4 H), 7.97 (t, J = 7.6 Hz, 1 H), 8.47 (d, J = 6.0
Hz, 2 H).
HRMS (ESI+): m/z [M + Na]+ calcd for C16H17N3NaO2S: 338.0934;
found: 338.0926.
13C NMR (100 MHz, CDCl3): d = 21.3, 126.7, 127.0, 129.2, 138.5,
Quinolinium N-Tosylimide (12)
1H NMR (400 MHz, CDCl3): d = 2.29 (s, 3 H), 7.09 (d, J = 8.0 Hz,
2 H), 7.55 (d, J = 8.0 Hz, 2 H), 7.63 (q, 1 H), 7.68–7.75 (m, 2 H),
7.96–7.98 (m, 1 H), 8.44 (d, J = 8.4 Hz, 1 H), 8.60–8.63 (m, 1 H),
9.09 (dd, J = 1.2, 5.6 Hz, 1 H).
138.6, 141.6, 145.1.
HRMS (ESI+): m/z [M + Na]+ calcd for C12H12N2NaO2S: 271.0512;
found: 271.0514.
13C NMR (100 MHz, CDCl3): d = 21.3, 76.4, 77.0, 77.6, 120.6,
121.0, 126.0, 126.4, 129.4, 130.0, 133.2, 139.3, 139.6, 141.1, 141.2,
146.7.
HRMS (ESI+): m/z [M + Na]+ calcd for C16H14N2NaO2S: 321.0668;
found: 321.0672.
2-Methylpyridinium N-Tosylimide (7)
1H NMR (400 MHz, CDCl3): d = 2.37 (s, 3 H), 2.43 (s, 3 H), 7.17
(d, J = 8.0 Hz, 2 H), 7.46 (td, J = 1.2, 7.6 Hz, 1 H), 7.51 (d, J = 8.0
Hz, 1 H), 7.56 (d, J = 8.0 Hz, 2 H), 7.87 (td, J = 1.2, 7.6 Hz, 1 H),
8.60 (dd, J = 1.2, 6.4 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 19.9, 21.3, 124.1, 126.4, 128.2,
Isoquinolinium N-Tosylimide (13)
129.4, 138.5, 140.7, 141.4, 146.4, 156.2.
1H NMR (400 MHz, CDCl3): d = 2.36 (s, 3 H), 7.16 (d, J = 8.0 Hz,
2 H), 7.66 (d, J = 8.0 Hz, 2 H), 7.81–7.86 (m, 2 H), 7.95–7.98 (m, 2
H), 8.06 (d, J = 8.0 Hz, 1 H), 8.13 (d, J = 6.0 Hz, 1 H), 9.29 (s, 1 H).
HRMS (ESI+): m/z [M + H]+ calcd for C13H15N2NaO2: 263.0849;
found: 263.0841.
13C NMR (100 MHz, CDCl3): d = 21.4, 124.6, 126.8, 127.2, 128.1,
4-Methylpyridinium N-Tosylimide (8)
1H NMR (400 MHz, CDCl3): d = 2.35 (s, 3 H), 2.52 (s, 3 H), 7.16
(d, J = 8.0 Hz, 2 H), 7.39 (d, J = 6.8 Hz, 2 H), 7.57 (d, J = 8.0 Hz,
2 H), 8.25 (d, J = 6.8 Hz, 2 H).
128.6, 129.3, 130.5, 134.2, 134.5, 137.8, 129.2, 140.5, 146.9.
HRMS (ESI+): m/z [M + Na]+ calcd for C16H14N2NaO2S: 321.0668;
found: 321.0665.
13C NMR (100 MHz, CDCl3): d = 21.4, 21.5, 127.1, 127.3, 129.2,
4-(1,3-Dioxolan-2-yl)pyridinium N-Tosylimide (14)
136.9, 141.4, 144.6, 144.6, 152.4.
1H NMR (600 MHz, CDCl3): d = 2.37 (s, 3 H), 3.96–4.10 (m, 4 H),
5.88 (s, 1 H), 7.19 (d, J = 8.0 Hz, 2 H), 7.63 (d, J = 8.0 Hz, 2 H),
7.69 (d, J = 5.8 Hz, 2 H), 8.47 (d, J = 5.8 Hz, 2 H).
HRMS (ESI+): m/z [M + Na]+ calcd for C13H14N2NaO2S: 285.0668;
found: 285.0683.
13C NMR (150 MHz, CDCl3): d = 21.4, 65.7, 100.2, 124.2, 127.1,
2-Bromo-4-methylpyridinium N-Tosylimide (9)
1H NMR (400 MHz, CDCl3): d = 2.37 (s, 3 H), 2.50 (s, 3 H), 7.16
(d, J = 8.0 Hz, 2 H), 7.38 (dd, J = 2.0, 6.4 Hz, 1 H), 7.59 (d, J = 8.0
Hz, 2 H), 7.65 (d, J = 2.0 Hz, 1 H), 8.81 (d, J = 6.4 Hz, 1 H).
129.3, 138.7, 141.7, 144.9, 150.1.
HRMS (ESI+): m/z [M + Na]+ calcd for C15H16N2NaO4S: 343.0723;
found: 343.0721.
13C NMR (100 MHz, CDCl3): d = 21.1, 21.4, 125.9, 126.9, 129.3,
2-(1,3-Dioxolan-2-yl)pyridinium N-Tosylimide (15)
1H NMR (600 MHz, CDCl3): d = 2.37 (s, 3 H), 3.97–4.03 (m, 4 H),
6.19 (s, 1 H), 7.18 (d, J = 8.2 Hz, 2 H), 7.55 (m, 1 H), 7.63 (d,
J = 8.2 Hz, 2 H), 7.83 (dd, J = 1.6, 7.9 Hz, 1 H), 7.91 (t, J = 7.7 Hz,
1 H), 8.83 (d, J = 6.3 Hz, 1 H).
132.6, 139.2, 140.2, 141.6, 147.5, 151.7.
HRMS (ESI+): m/z [M + Na]+ calcd for C13H13BrN2NaO2S:
362.9773; found: 362.9793.
Synthesis 2007, No. 10, 1459–1464 © Thieme Stuttgart · New York