1944
D. Kontrec et al. / Tetrahedron: Asymmetry 10 (1999) 1935–1945
128.89, 142.70, 148.17. Anal. calcd for C24H20N4Cl2 (435.34): C, 66.21; H, 4.63; N, 12.87%. Found: C,
66.20; H, 4.70; N, 12.78%.
3.3. 2,4,5-Tri-N-((R)-10-phenylethylamino)-5-chloro-1,3-dicyanobenzene 4
Compound 1 (0.50 g, 1.9 mmol) and (R)-PEA (2.28 g, 18.8 mmol) were heated at 150°C oil
temperature for 20 h. The reaction mixture was diluted with MeOH (1.0 ml) and applied onto a silica
1
gel column (50 g). Elution by toluene afforded 0.90 g (92%) of pure 2, slightly coloured oil. H NMR:
1.24 (d, 3H, J=6.4 Hz), 1.48 (d, 6H, J=6.4 Hz), 4.73 (d, 1H, J=8.5 Hz), 5.09 (d, 2H, J=8.2 Hz), 5.18
(dq, 1H, J1=8.5 Hz, J2=6.4 Hz), 5.44 (dq, 2H, J1=8.2 Hz, J2=6.4 Hz), 7.23–7.48 (m, 15H); 13C NMR:
22.46, 23.89, 54.12, 54.81, 79.02, 99.07, 117.35, 126.01, 126.30, 127.50, 128.60, 128.69, 142.62, 142.97,
149.59, 155.28. Anal. calcd for C32H30N5Cl (520.01): C, 73.89; H, 5.81; N, 13.46%. Found: C, 73.64;
H, 5.55; N, 13.40%.
3.4. General procedure for preparation of 5–8
Optically inactive compounds 2–4 (1.0 g) were prepared from 1 and racemic (R)-PEA following
the same procedures as described above for the enantiomerically pure compounds. Crude products
were dissolved in MeOH (25.0 ml), and to the ice-cooled solution conc. sulfuric acid (10.0 ml) was
added dropwise. After 10 min stirring at ambient temperature, water (300 ml) was added, the resulting
precipitate collected on filter and washed, first with dil. sodium bicarbonate solution, then with water.
3.4.1. 4-Amino-2,5,6-trichloro-1,3-dicyanobenzene 5
Yield: 435 mg (61.9%), mp 284–285°C. IR: 3420, 3320, 3220, 2220, 1640, 1570, 1540, 1460, 1290,
1
1220, 1210, 1030, 850, 740 cm−1; H NMR (DMSO-d6): 7.91 (s, 2H); 13C NMR (DMSO-d6): 95.43,
100.23, 113.93, 116.96, 139.17, 140.03, 151.96. Anal. calcd for C8H2N3Cl3 (246.47): C, 38.98; H, 0.81;
N, 17.05%. Found: C, 38.73; H, 1.21; N, 16.58%.
3.4.2. 4,6-Diamino-2,5-dichloro-1,3-dicyanobenzene 6
Yield: 469 mg (90.2%), mp 336–338°C. IR: 3460, 3360, 3240, 2220, 1620, 1450, 1350, 1240, 770,
1
740 cm−1; H NMR (DMSO-d6): 6.92 (s, 4H); 13C NMR (DMSO-d6): 86.60, 98.26, 114.78, 139.86,
150.36. Anal calcd for C8H4N4Cl2 (227.05): C, 42.31; H, 1.77; N, 24.68%. Found: C, 42.36; H, 2.05; N,
24.24%.
3.4.3. 2,4,6-Triamino-5-chloro-1,3-dicyanobenzene 7
Yield: 303 mg (76.0%), mp 327–328°C. IR: 3480, 3350, 3240, 2200, 1630, 1590, 1560, 1480, 1460,
1
1350, 1250, 790, 750 cm−1; H NMR (DMSO-d6): 6.11 (s, 2H), 6.28 (s, 4H); 13C NMR (DMSO-d6):
70.86, 89.20, 116.50, 150.53, 153.98. Anal. calcd for C8H6N5Cl (207.62): C, 46.27; H, 2.91; N, 33.73%.
Found: C, 46.33; H, 3.07; N, 33.47%.
1
3.5. H NMR experiments of chiral recognition
Solutions of 2–4 (0.05 mmol) and racemic compounds, 3,5-dinitrobenzoyl-10 -phenylethylamide,
benzoyl-10-phenylethylamide, N-3,5-dinitrobenzoylglycine isopropylester, Tröger’s base (0.05 mmol), in
CDCl3 (0.5 ml) were prepared in the NMR tube and the spectra run at ambient temperature. Comparison
with the NMR spectra in the absence of chiral selector revealed no separation of the enantiotopic protons.