Y. Peng, G. Song / Tetrahedron Letters 45 (2004) 5313–5316
5315
1650, 1625; dH (DMSO-d6): 6.76 (4H, s, NH2), 7.27 (2H,
t, J ¼ 8:9 Hz, Ph), 8.25 (2H, t, J ¼ 8:9 Hz, Ph); MS (EI)
m=z 205 (Mþ).
100
80
60
40
20
0
2,4-Diamino-6-(4-methylphenyl)-1,3,5-triazine (2e): mp ¼
244–245 °C (lit.:11 244 °C); mmax (KBr, cmÀ1): 3480, 3240,
1660, 1590. dH (DMSO-d6): 2.30 (3H, s, CH3)), 6.47 (4H,
s, NH2), 7.20 (2H, d, J ¼ 8:0 Hz, Ph), 8.20 (2H, d,
J ¼ 8:3 Hz, Ph); MS (EI) m=z 201 (Mþ).
1
2
3
4
5
Reaction cycles
2,4-Diamino-6-(2,4-dichloro-phenyl)-1,3,5-triazine (2h):
mp ¼ 206–207 °C (lit.:22 204–206 °C); mmax (KBr, cmÀ1):
3330, 3160, 1670, 1655; dH (DMSO-d6): 6.58 (s, 2H,
NH2), 7.27–7.38 (m, 2H, ArH), 7.50–7.63 (m, 1H, ArH);
MS (EI) m=z 256 (Mþ).
Figure 2. Recycling study of model reactions.
In summary, for the first time, we have developed an
efficient, convenient and practicalconversion of ary-l
nitriles into arylguanamines using computer-controlled
microwave irradiation in conjunction with a green sol-
vent [bmim][PF6]. This new method has severaladvan-
tages over its counterpart carried out in traditional
organic solvents under conventional heating: (1) dra-
matically reduced reaction time, (2) good yields, (3)
simple manipulation, and (4) safe reaction medium.
2,4-Diamino-6-piperonyl-1,3,5-triazine (2i): mp ¼ 260–
261 °C (lit.:23 257–258 °C); mmax (KBr, cmÀ1): 3510, 3390,
1660, 1630, 1260; dH (DMSO-d6): 6.25 (s, 2H, NH2),
6.56 (s, 2H, OCH2O), 6.75–6.93 (m, 3H, ArH); MS (EI)
m=z 231 (Mþ).
Acknowledgements
2. Experimental
Financialsupport from the NSFC (Grant 20376022)
and Shanghai Education Committee are gratefully
acknowledged. We also thank Personal Chemistry AB
(Uppsala, Sweden) for the use of their instrument.
Arylnitriles were purchased or prepared in good yields
by standard dehydration method from aldoximes. Di-
cyandiamide and [bmim][PF6] were obtained from
commercialsources and used as received. Reactions
were carried out on EmrysTM Optimizer single-mode
microwave parallel synthesizer (Personal Chemistry
Ltd., Uppsala, Sweden). All products were known
compounds and gave physical(mps) and spectral(FT-
IR, 1H NMR and MS) data consistent with the assigned
structures. Melting points were determined with a
References and notes
1. Smolin, E. M.; Rapoport, L. s-Triazines and Derivatives;
Interscience: New York, 1959. Chapter IV, p 217.
2. Tanaka, N.; Fukue, Y.; Mizusawa, K.; Ishikawa, M. WO
9724338, 1997; Chem. Abstr. 1997, 127, 149763.
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Chem. Abstr. 1987, 106, 34062).
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516–518.
5. Flood, L. A.; Gupta, R. B. WO 9604258, 1996; Chem.
Abstr. 1996, 124, 345097.
€
BUCHI B-540 digitalapparatus and were uncorrected.
IR spectra were recorded in a Nicolet Nexus 470 FT-IR
spectrophotometer in KBr. 1H NMR spectra were
measured in a Bruker AM 500 (500 MHz) spectrometer
using TMS as the internalstandard. MS spectra were
recorded on a Hitachi M-80 mass spectrometer.
6. Oishi, R.; Utaka, K.; Ono, K.; Ohki, M.; Yasue, T. EP
348550, 1990; Chem. Abstr. 1990, 112, 212501.
7. Kalab, J.; Moravek, J. CS 254623, 1988; Chem. Abstr.
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01117863, 1989; Chem. Abstr. 1989, 111, 194802.
10. (a) Beijer, F. H.; Kooijiman, H.; Spek, A. L.; Sijbesma, R.
P.; Meijer, E. W. Angew. Chem., Int. Ed. 1998, 37, 75–78;
(b) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem.
1997, 62, 836–839; (c) Beijer, F. H.; Sijbesma, R. P.;
Vekemans, J. A. J. M.; Meijer, E. W.; Kooijiman, H.;
Spek, A. L. J. Org. Chem. 1996, 61, 6371–6380.
11. Lalezari, I.; Golgolab, H. J. Chem. Eng. Data 1971, 16,
117.
General procedure. A suspension of a mixture of aryl-
nitrile (10 mmol), dicyandiamide (0.93 g, 11 mmol) and
powdered KOH (0.11 g, 2 mmol) in [bmim][PF6] (3 mL)
was subjected to microwave irradiation (temperature
setting: 130 °C) for an optimized period listed in Table 1.
After cooling to room temperature, the precipitate was
collected by filtration, washed with hot water and re-
crystallized from ethanol–DMF (5:1, v/v) to afford 6-
aryl-2,4-diamino-1,3,5-triazine.
2,4-Diamino-6-phenyl-1,3,5-triazine (2a): mp ¼ 229–
230 °C (lit.:11 228 °C); mmax (KBr, cmÀ1): 3450, 3340,
1625, 1560; dH (DMSO-d6): 6.55 (4H, s, NH2), 7.44–7.56
(3H, m, Ph), 8.48 (2H, d, J ¼ 6:8 Hz, Ph); MS (EI) m=z
187 (Mþ).
12. Smyrl, N. R.; Smithwick, R. W., III. J. Heterocycl. Chem.
1982, 19, 493–496.
2,4-Diamino-6-(4-fuorophenyl)-1,3,5-triazine (2c): mp ¼
251–252 °C (lit.:11 249 °C); mmax (KBr, cmÀ1): 3500, 3390,
13. For recent books and reviews, see: (a) Hayes, B. L.
Microwave Synthesis: Chemistry at the Speed of Light;