Unless otherwise stated, all chemical reagents were purchased from Acros, Aldrich, or Fluka USA. Flash column chromatography was performed using Merck silica gel (60, particle size 0.02–0.03 mm). 1H and 13C NMR spectra were recoZrded using Bruker AM-500 or AM-600 spectrometers. Chemical shifts are reported in ppm (δ) with the solvent relative to tetramethylsilane (TMS) employed as the internal standard (residual CHCl3, δH 7.26 ppm; CDCl3, δc 77 ppm). The following abbreviations were used to δ designate multiplicities: s = singlet, d = doublet, t = triplet, m = multiplet. Infrared spectra were recorded on a Mattson Galaxy Series FTIR 3000 spectrometer; peaks are reported in cm−1. Elemental analyses were obtained on Elemental Analyzer AE-3000. High-resolution mass spectra (HRMS) were obtained on a Micro GCT-MS equipped with an EI ion source. Optical rotations were measured on a WZZ-1 automatic polarimeter with a 2-cm cell, recorded at the sodium d-line.
The procedure for the synthesis of the complexes 1–15
1-[2-(4-isobutyl-4,5-dihydro-oxazol-2-yl)-ethyl]-piperidine zinc(II) dichloride, 1
A dry 100 mL Schlenk flask was purged with N2 and charged with anhydrous ZnCl2 (2.515 g, 18.45 mmol), 3-piperidin 1-yl propionitrile (2.462 g, 17.81 mmol) and l-leucinol (4.824 g, 41.16 mmol). 40 mL of chlorobenzene was added, and the reaction mixture was refluxed for 72 h. After cooling to room temperature, the solvent was removed under reduced pressure, and the residue was dissolved in 15 mL of H2O and extracted with CH2Cl2 (3 × 20 mL). The combined organic extracts were evaporated to give a crude red oil, which was purified by column chromatography (petroleum ether/CH2Cl2, 4/1) to afford the title compound as colourless crystals in 25% yield, m.p. 50–52 °C \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +67.5° (c = 0.02, MeOH); δH (600 MHz, CDCl3, 27 °C) 4.52–4.56 (m, 1H), 4.12–4.16 (m, 1H), 4.01–4.03 (m, 1H), 2.89–2.92 (m, 1H), 2.73–2.75 (m, 1H), 2.59–2.64 (m, 3H), 2.31 (t, J = 12.4 Hz, 1H), 1.62–1.78 (m, 6H), 1.43–1.44 (m, 2H), 1.29–1.35 (m, 2H), 1.15–1.20 (m, 1H), 0.84–0.90 (m, 6H); δC (150 MHz, DMSO-d6), 170.0, 73.7 (×2), 65.5, 62.9 (×2), 54.7, 46.1, 44.4, 43.3, 25.1, 24.0, 23.4, 22.6. νmax(cm−1) 3274, 2954, 2869, 1648, 1587, 1468, 1387, 1368, 1319, 1283, 1169, 1076 1041, 979, 956, 949, 904, 864, 839, 780, 607, 493. Found C: 45.36, H: 7.19, N: 7.75%; C14H26Cl2N2OZn requires C: 44.88, H: 7.00, N: 7.48%.
Bis-[4-isopropyl-2-methyl-4,5-dihydro-oxazole]zinc(II) dichloride, 2
Prepared using the same procedure described above for complex 1, from a mixture of ZnCl2 (5.401 g, 39.63 mmol), 3-piperidin1-yl propionitrile (2.321 g, 16.79 mmol) and l-valinol (5.319 g, 51.56 mmol) in chlorobenzene (80 mL). The product was obtained as colourless crystals in 65% yield after column chromatography (petroleum ether/CH2Cl2, 2/1), m.p. 60–62 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +9.97° (c = 0.35, MeOH); δH (600 MHz, CDCl3, 27 °C) 3.64–3.71 (m, 6H), 2.03 (s, 6H), 1.85–1.88 (m, 2H), 0.92 (d, J = 6.8 Hz, 6H), 0.96 (d, J = 7.8 Hz, 6 H); δC (150 MHz, CDCl3), 171.2(×2), 63.7, 63.6, 57.1, 53.5, 31.7, 28.9, 23.4, 22.9, 19.3, 19.0, 18.8, 17.9; νmax(cm−1) 3436, 3284, 3145, 2954, 2864, 1725, 1659, 1585, 1458, 1420, 1393, 1319, 1278, 1280, 1219, 1092, 1038, 974, 952, 905, 765. Found C: 43.49, H: 7.19, N: 7.23%; C14H26Cl2N2O2Zn requires C: 43.04, H: 6.71, N: 7.17%.
α-Phenyl-1-hexahydropyridyl ethylamine zinc(II), 3
Prepared using the same procedure described above, using anhydrous ZnCl2 (3.5002 g, 25.68 mmol), 3-piperidin1-yl propionitrile (2.4590 g, 17.79 mmol), and l-phenylalaninol (5.5420 g, 40.40 mmol) in 80 mL of dry chlorobenzene. The product was obtained as colorless crystals after column chromatography (petroleum ether/dichloromethane, 1/2) in 86% yield, m.p: 168–172 °C; \( \left[ {{\text{a}}} \right]_{\text{D}^{25}} \) = −29.30º (c = 0.016, CH3OH): δH (600 MHz, CDCl3, 27 °C) 7.32–7.43 (m, 5H), 4.23–4.32 (m, 1H), 3.42–3.64 (m, 3H), 2.96–3.05 (m, 2H), 2.61–2.65 (m, 1H), 2.19–2.41 (t, J = 912.4 Hz, 1H), 1.62–1.78 (m, 6H), 1.43–2.41 (m, 3H), 1.69–1.98 (m, 6H), 1.24–1.31 (m, 1H), δC (150 MHz, DMSO-d6), 169.2, 141.8, 128.9, 128.4, 127.4, 127.3, 127.1 65.2, 65.1, 55.4, 55.2, 53.8, 51.9, 25.3, 23.2(×2); νmax: 3447, 3027,2943, 2860, 1648, 1603, 1496, 1455, 1132, 1043, 1060,1040, 1030, 762, 705. Elemental analysis: Found C: C:47.20%, H, 6.05%, N, 7.60%; C14H22Cl2N2Zn requires C: 47.42, H: 6.25, N: 7.90%.
2-Morpholin-4-(R)-yl-1-phenyl-ethylamine zinc(II) dichloride complex, 4
Prepared as described above, from a mixture of anhydrous ZnCl2 (1.780 g, 13.06 mmol), N-cyanoacetylmorpholine (1.501 g, 9.74 mmol), d-phenylglycinol (4.097 g, 29.87 mmol) and dry chlorobenzene (40 mL). The reaction mixture was refluxed for 60 h. The product was purified by column chromatography (petroleum ether/CH2Cl2, 1/100) to afford the title compound as colourless crystals in 90% yield, m.p. 196–198 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = −42.43° (c = 0.13, THF); δH (500 MHz, DMSO-d6, 27 °C), 7.48 (d, J = 8.8 Hz, 2H), 7.36 (t, J = 7.5 Hz, 2H), 7.30 (t, J = 7.3 Hz, 1H), 4.95 (br s, 2H), 4.14 (t, J = 11.9 Hz, 1H), 3.88-3.91 (m, 2H), 3.78–3.81 (m, 2H), 2.97–3.00 (m, 2H), 2.67–2.82 (m, 4H); δC (125 MHz, DMSO-d6) 139.9, 128.5 (×2), 127.9, 127.0 (×2), 65.6, 65.2 (×2), 54.6 (×2), 51.2; νmax(cm−1) 3435, 3271, 3228, 3145, 2974, 2928, 2904, 2865, 1591, 1499, 1458, 1447, 1290, 1263, 1146, 1126, 1094, 1072, 1060, 1037, 988, 899, 874, 749, 694. Found C: 42.39, H: 5.24, N: 8.05%; C12H18N2Cl2OZn requires C: 42.07, H: 5.30, N: 8.18%.
(1-Methyl-piperazine)zinc(II) trichloride, 5
Prepared using the same procedure described for complex 5, from a mixture of anhydrous ZnCl2 (5.008 g, 36.75 mmol), 1-(2-cyanoethyl)-4-methylpiperazine (2.313 g, 15.09 mmol) and d-phenylglycinol (10.696 g, 77.97 mmol) in 40 mL of dry chlorobenzene. The product was recrystallized from ethanol/CH2Cl2, to furnish colourless crystals in 56% yield; m.p. 148–152 °C; δH (600 MHz, CDCl3 and DMSO-d6, 27 °C) 4.09–4.12 (m, 1H), 3.64–3.67 (m, 1H), 3.56–3.59 (m, 1H), 2.86–2.88 (m, 4H), 2.37–2.40 (m, 3H), 2.16 (s, 3H); δC (150 MHz, CDCl3 and DMSO-d6) 62.1, 54.7, 51.4, 44.0, 42.5. νmax(cm−1) 3491, 3455, 3189, 3006, 2956, 2771, 1585, 1458, 1387, 1128, 1099, 1058, 1035, 998, 976, 870, 701. Found: C: 22.20, H: 4.56, N: 10.10%; C5H13Cl3N2Zn requires C: 22.01, H: 4.80, N: 10.27%.
2-[4R-4,5-dihydro-4-(1′,1′-dimethylethyl)-3-oxazolinyl]aniline zinc(II) dichloride, 6
Prepared using the same procedure described for complex 1, from a mixture of anhydrous ZnCl2 (3.002 g, 22.02 mmol), 3-amino-benzonitrile (6.702 g, 56.73 mmol), and d-leucinol (10.008 g, 85.40 mmol) in 80 mL of dry chlorobenzene. The reaction mixture was refluxed for 72 h. After evaporation, the residue was dissolved in 15 mL of H2O and extracted with CH2Cl2 (3 × 10 mL). The organic layer was evaporated under vacuum, and the red oily residue was purified by column chromatography over silica gel (petroleum ether/CH2Cl2, 1/4), yield: 90%; m.p. 168–170 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = −54.9° (c = 0.0364, EtOH). δH (600 MHz, CDCl3 and DMSO-d6, 27 °C) 7.77–7.90 (m, 1H), 6.98–7.19 (m, 5H), 6.63–6.76 (m, 2H), 5.19–5.33 (m, 1H), 4.26–4.58 (m, 4H), 3.92–3.93 (m, 1H), 3.21–3.25 (m, 4H), 1.70–1.82 (m, 4H), 1.35–1.44 (m, 2H), 0.89–0.96 (m, 12H); δC (150 MHz, CDCl3 and DMSO-d6) 167.0, 161.3, 146.9, 146.4, 134.2, 126.9, 115.0, 113.9, 113.0, 112.8, 111.5(×2), 109.9(×2), 70.9, 63.0, 46.5, 45.3, 43.7, 39.5, 23.5, 23.2, 21.5, 21.1, 21.0, 20.3; νmax(cm−1) 3353, 2957, 2928, 2870, 1625, 1498, 1467, 1386, 1333, 1290, 1171, 1135, 1108, 996, 966, 948, 882, 797, 750, 688, 576, 537. Found C: 54.65, H: 6.24, N: 10.16%; C26H36N4Cl2O2Zn requires C: 54.51, H: 6.33, N: 9.78%.
Bis-[2-(4R-benzyl-4,5-dihydro-oxazol-2-yl)-pyridine]zinc(II) tetrachlorozincate, 7
Prepared using the same procedure described for compound 1, using anhydrous ZnCl2 (3.340 g, 24.51 mmol), 2-cyanopyridine (2.095 g, 20.13 mmol) and l-phenylalaninol (3.992 g, 26.40 mmol) in 40 mL of dry chlorobenzene, and the reaction mixture was refluxed for 60 h. The product was extracted into CH2Cl2 as described above, and purified by column chromatography (petroleum ether/CH2Cl2, 1/4) to give colourless crystals in 80% yield; m.p. 134–136 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +51.4° (c = 0.0272, MeOH); δH (600 MHz, DMSO-d6, 27 °C) 8.78–8.81 (m, 2H), 7.95–8.03 (m, 4H), 7.63–7.68 (m, 2H), 7.22–7.30 (m, 10H), 4.64–4.67 (m, 4H), 4.49–4.51 (m, 2H), 3.30–3.39 (m, 2H), 3.35 (s, 2H), 2.82–2.86 (m, 2H); δC (150 MHz, DMSO-d6) 163.8, 148.5, 137.7, 135.5, 128.2, 127.6, 126.7, 125.7, 122.4, 73.6, 64.5, 39.2; νmax(cm−1) 3493, 3061, 3027, 2955, 2920, 2853, 1660, 1590, 1571, 1492, 1469, 1452, 1440, 1404, 1388, 1325, 1293, 1244, 1223, 1154, 1143, 1088, 1045, 1014, 947, 847, 801, 746, 703, 681, 632; Found C: 57.43, H: 5.03, N: 8.67%; C30H30Cl2N4O3Zn2 requires C: 57.12, H: 4.79, N: 8.88%.
[2-(4S-isopropyl-4,5-dihydro-oxazol-2-yl)-pyridine] zinc (II) dichloride, 8
Prepared using the procedure described above for compound 1, refluxing a mixture of anhydrous ZnCl2 (3.423 g, 25.12 mmol), 2-cyanopyridine (2.128 g, 20.44 mmol), and l-valinol (3.386 g, 32.82 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was purified by column chromatography (petroleum ether/CH2Cl2, 1/8). Colourless crystals were obtained in 85% yield; m.p. 178–180 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +23.1° (c = 0.17, MeOH); δH (600 MHz,CDCl3, 27 °C) 8.78–8.80 (m, 1H), 8.20–8.23 (m, 1H), 8.05 (d, J = 7.7 Hz, 1H), 7.86–7.88 (m, 1H), 4.96 (t, J = 9.5 Hz, 1H), 4.65 (t, J = 8.9 Hz, 1H), 4.42–4.45 (m, 1H), 2.10–2.14 (m, 1H), 1.04–1.14 (m, 6H); δC (150 MHz, CDCl3) 166.1, 149.8, 141.2, 140.2, 129.7, 124.1, 75.4, 69.3, 31.6, 18.4, 17.8; νmax(cm−1) 3223, 3188, 2962, 2875, 1662, 1587, 1470, 1392, 1372, 1320, 1251, 1129, 1046, 878, 836, 791, 752, 690, 539. Found C: 40.81, H: 3.85, N: 8.47%; C11H14Cl2N2OZn requires C: 40.46, H: 4.32, N: 8.58%.
[1, 2-bis–(4R-phenyl-4,5-dihydro-oxazol-2-yl)phenyl] zinc(II) dichloride, 9
Prepared using the same procedure described above for compound 1, using anhydrous ZnCl2 (2.590 g, 19.01 mmol), isophthalonitrile (3.353 g, 26.17 mmol), and d-phenylglycinol (8.492 g, 61.91 mmol) in 80 mL of dry chlorobenzene, and refluxing for 72 h. The product was purified by column chromatography (petroleum ether/CH2Cl2, 1/8). Yield = 86%; m.p. >250 °C (dec), \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = −54.9° (c = 0.0364, EtOH).δH (600 MHz, CDCl3, 27 °C) 7.77–7.79 (m, 2H), 7.55–7.56 (m, 2H), 7.18–7.28 (m, 10H), 5.28 (t, J = 9.2 Hz, 2H), 4.68 (t, J = 9.2 Hz, 2H), 4.10 (t, J = 8.4 Hz, 2H),δC (150 MHz, CDCl3) 163.5, 140.3, 129.4 (×2), 128.4, 127.0 (×2), 126.0,125.3 (×2), 73.9, 68.3. νmax(cm−1) 3447, 3058, 2965, 2907, 1650, 1639, 1592, 1495,1473, 1455, 1379, 1363, 1318, 1308, 1278, 1238, 1207, 1153, 1120, 1067, 1020, 991, 945, 760, 704, 648, 594, 556. Found C: 56.92, H: 3.92, N: 5.41%; C24H20Cl2N2O2Zn requires C: 57.11, H: 3.99, N: 5.55%.
2-{(4S-isopropyl-4,5-dihydro-oxazol-2-yl)-phenyl-4,5-dihydro-imidazol-1-yl}-3-methyl-butan-1-ol zinc(II), 10
Prepared using the same procedure described for compound 1, refluxing a mixture of anhydrous ZnCl2 (4.000 g, 29.35 mmol), isophthalonitrile (6.700 g, 52.29 mmol), and l-valinol (16.000 g, 15.51 mmol) in 80 mL of dry chlorobenzene for 72 h. The product was purified by column chromatography (petroleum ether/CH2Cl2, 1/4). Yield: 90%; m.p. >250 °C (dec), \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +34.4° (c = 0.0436, CHCl3),δH (600 MHz, DMSO-d6, 27 °C), 7.78–7.81 (m, 2H), 7.69–7.71 (m, 1H), 7.63–7.66 (m, 1H), 4.90–4.93 (m, 1H), 4.65 (t, J = 9.4 Hz, 1H), 4.51–4.55 (m, 1H), 4.45 (t, J = 7.8 Hz, 2H), 4.27 (t, J = 5.0 Hz, 1H), 3.75 (d, J = 11.2 Hz, 1H), 3.62–3.65 (m 2H), 3.47–3.50 (m, 1H), 2.21–2.24 (m, 1H), 1.70–1.74 (m, 1H), 0.94–0.99 (m, 8H), 0.85–0.86 (m, 4H), 0.72 (d, J = 6.6 Hz, 3H), 0.59 (d, J = 6.6 Hz, 3H); δC (150 MHz, CDCl3 and DMSO-d6) 165.6, 163.1, 130.2, 129.4, 128.7 (×2), 125.4, 123.5, 68.4, 67.7, 64.2, 61.1, 57.5, 42.5, 29.9, 29.4, 27.0, 25.1, 17.9, 17.5, 16.9, 16.2, 13.9, 13.0. Found C: 53.55, H: 6.87, N: 7.78%; C23H35N3Cl2O2Zn requires C: 52.94, H: 6.76, N: 8.05%. νmax(cm−1) 3436, 2961, 2923, 2874, 1635, 1604, 1571, 1520, 1464, 1377, 1317, 1300, 1138, 1074, 1047, 1026, 946, 784, 766.
Bis-[(4S-isobutyl-4,5-dihydro-oxazol-2-yl)-acetonitrile] zinc(II), 11 [11]
Prepared using the procedure described above for compound 1, by refluxing a mixture of anhydrous ZnCl2 (0.450 g, 3.30 mmol), tetracyanoethylene (1.000 g, 7.81 mmol), and l-leucinol (4.029 g, 34.38 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was obtained in 88% yield as colourless crystals after column chromatography (petroleum ether/dichlormethane, 4/1). m.p. > 220 °C (dec); \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +166.33° (c = 0.30, CH2Cl2): δH (500 MHz, CDCl3, 27 °C) 4.60 (t, J = 7.3 Hz, 4H), 3.94–4.05 (m, 8H), 1.29–1.72 (m, 12H), 0.89–0.93 (m, 24H); δC (125 MHz, CDCl3) 170.1, 118.3, 73.0, 61.6, 45.6, 25.0, 22.3, 21.8. νmax(cm−1) 3439, 2955, 2927, 2871, 2201, 1611, 1530, 1430, 1386, 1368, 1342, 1281, 1260, 1239 1218, 1133, 1068, 1048, 951, 746. Found: C: 59.32, H: 7.46, N: 13.77%; C32H48N6O4Zn requires C: 59.48, H: 7.49, N: 13.01%.
Bis-[(4S-phenyl-4,5-dihydro-oxazol-2-yl)-acetonitrile] zinc(II), 12 [12]
Prepared using the procedure described above for compound 1, by refluxing a mixture of anhydrous ZnCl2 (0.450 g, 3.30 mmol), tetracyanoethylene (1.000 g, 7.81 mmol), and L-phenylglycinol (10.089 g, 7.35 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was obtained in 86% yield as colourless crystals after column chromatography (petroleum ether/CH2Cl2, 2/1) m.p. > 220 °C (dec), \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +306.6° (c = 0.17, CH2Cl2). δH (500 MHz, CDCl3, 27 °C) 7.22–7.26 (m, 12H), 6.82 (d, J = 6.9 Hz, 8H), 4.50–4.60 (m, 8H), 3.95 (t, J = 7.2 Hz, 4H); δC (125 MHz, CDCl3) 171.3, 138.6, 129.3 (×2), 129.1, 126.8 (×2), 118.5, 74.6, 67.4; νmax(cm−1) 3032, 2903, 2202, 1608, 1526, 1429, 1455, 1362, 1264, 1220, 1075, 1051,911, 734, 701. Found C: 65.99, H: 4.20, N: 11.28%; C40H32N6O4Zn requires C: 66.17, H: 4.44, N: 11.57%.
[3-(4S-isopropyl-4,5-dihydro-oxazol-2-yl)-6-methyl-2-ol]zinc(II) chloride dimer, 13
Prepared using the procedure described above for compound 1, by refluxing a mixture of anhydrous ZnCl2 (3.502 g, 25.70 mmol), 2-hydro-6-methyl-nicotinonitrile (2.002 g, 14.92 mmol) and l-valinol (8.025 g, 77.79 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was obtained in 80% yield as colourless crystals after column chromatography (petroleum ether/CH2Cl2, 4/1) m.p. 168–170 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = +162.8° (c = 0.181, MeOH); δH (600 MHz, CDCl3 and DMSO-d6, 27 °C) 12.36(br s, 1H), 8.27 (d, J = 7.7 Hz, 2H), 6.57 (d, J = 7.7 Hz, 2H), 4.56–4.58 (m, 2H), 4.50–4.53 (m, 2H), 4.37–4.39 (m, 2H), 2.68 (s, 6H), 2.16–2.18 (m, 2H), 0.99 (d, J = 6.9 Hz, 6H), 0.93 (d, J = 6.7 Hz, 6H); δC (150 MHz, DMSO-d6)164.0, 162.5, 155.1 (×2), 146.7 (x4), 110.1 (×2), 108.5 (×2), 69.6 (×2), 68.2 (×2), 30.0 (×2), 20.1 (×2), 18.9 (×2), 15.0 (×2); νmax(cm−1) 3420, 2962, 2928, 2874, 1726, 1660, 1612, 1564, 1388, 1325, 1214, 1150, 1084, 986, 953, 790, 750, 701, 597, 469. Found C: 37.52, H: 4.22, N: 7.28%; C25H32Cl6N4O4Zn2 (CHCl3 solvate) requires C: 37.72, H: 4.05, N: 7.04%.
Tetra-[3-(4S-isobutyl-4,5-dihydro-oxazol-2-yl)-6-methyl-2-ol] zinc(II) chloride, 14
Prepared using the procedure described above for compound 1, by refluxing a mixture of anhydrous ZnCl2 (1.500 g, 11.01 mmol), 2-hydro-6-methyl-nicotinonitrile (1.002 g, 7.47 mmol) and L-leucinol (4.022 g, 34.32 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was obtained in 86% yield as colourless crystals after column chromatography (petroleum ether/CH2Cl2, 1/1). m.p. 120–124 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) =+30.0° (c = 0.08, THF). δH (600 MHz, CDCl3, 27 °C), 8.02 (d, J = 7.8 Hz, 2H), 7.98 (d, J = 7.8 Hz, 2H), 6.15 (d, J = 5.5 Hz, 2H), 6.14 (d, J = 5.4 Hz, 2H), 4.86 (t, J = 8.7 Hz, 2H), 4.48–4.56 (m, 6H), 4.29 (d, J = 7.8 Hz, 1H), 4.28 (d, J = 7.9 Hz, 1H), 3.94 (t, J = 8.6 Hz, 2H), 2.41(s, 6H), 2.44(s, 6H), 1.90–1.94 (m, 2H), 1.57–1.69 (m, 6H), 1.21–1.43 (m, 4H), 0.82 (t, J = 7.5 Hz, 12H), 0.74 (d, J = 6.6 Hz, 6H), 0.57 (d, J = 6.6 Hz, 6H). δC (150 MHz, CDCl3) 167.7, 167.5, 165.3, 164.8, 163.4, 163.2, 143.4, 143.3, 111.7, 111.5, 105.3, 105.1, 73.0, 72.8, 63.8, 63.4, 43.9, 43.1, 26.1 (×2), 25.3, 25.2, 22.7, 22.6, 22.5 (×2); νmax(cm−1) 2957, 2929, 2870, 1648, 1579, 1490, 1386, 1322, 1284, 1250, 1205, 1153, 1077, 1060, 953, 883, 787, 749, 707, 620, 595, 419. Found C: 46.98, H: 5.12, N: 7.99%; C52H68Cl4N8O8Zn4 requires C: 46.73, H: 5.13, N: 8.38%.
Tetra-{3-[4(R)-benzyl-4,5-dihydro-oxazol-2-yl]-6-methyl-2-ol}zinc complex, 15
Prepared using the procedure described above for compound 1, by refluxing a mixture of anhydrous ZnCl2 (1.562 g, 11.46 mmol), 2-hydro-6-methyl-nicotinonitrile (1.000 g, 7.46 mmol), and D-phenylalaninol (4.008 g, 26.51 mmol) in 40 mL of dry chlorobenzene for 60 h. The product was obtained in 82% yield as colourless crystals after column chromatography (petroleum ether/CH2Cl2, 1/2). m.p. 120–124 °C, \( \left[ {\alpha } \right]_{\text{D}}^{25} \) = −109.0° (c = 0.164, THF); δH (600 MHz, DMSO-d6, 27 °C) 12.36–12.41 (m, 3H), 9.78 (d, J = 8.0 Hz, 4H), 8.11 (d, J = 7.2 Hz, 2H), 7.13–7.22 (m, 17H), 6.23(d, J = 7.2 Hz, 2H), 4.90 (s, 3H), 4.08 (d, J = 5.2 Hz, 3H), 3.34–3.40 (m, 6H), 2.84–2.88 (m, 4H), 2.69–2.73 (m, 4H), 2.23 (s, 12H),δC (150 MHz, DMSO-d6) 162.7, 162.4, 150.3, 143.5, 138.5, 128.9 (×2), 127.8 (×2), 125.7, 116.7, 105.4, 61.6, 51.8, 36.6, 18.3. νmax(cm−1) 3435, 3061, 2922, 1644, 1581, 1488, 1454, 1385, 1323, 1245, 1206, 1152, 1085, 1059, 1031, 986, 968, 786, 784, 704, 619, 510. Found C: 52.03, H: 4.38, N: 7.25%; for C64H60N8O8Zn4Cl4 requires C: 52.20, H: 4.11, N: 7.61%.