Synthesis and Spectroscopic Properties of a Novel Bis-spirocalixarene

Abstract

A convenient synthesis of the first spiro-bound calix[4]arene containing fluorenyl moieties at the para-position is presented. Dynamic NMR effects of the spiro-calixarene 4 are in ­accord with a preferred partial-cone conformation.

calixarenes - oxidation - spiro compounds - ligands - iron

References and Notes

1 Mitschke U. Bäuerle P. J. Mater. Chem.  2000,  10:  1471 ; and references cited herein

2a Gutsche CD. Calixarenes   The Royal Society of Chemistry; Cambridge: 1989. 

2b Calixarenes: A Versatile Class of Macrocyclic Compounds   Vicens J. Böhmer V. Kluwer; Dordrecht: 1991. 

2c Gutsche CD. Calixarenes Revisited   The Royal Society of Chemistry; Cambridge: 1998. 

2d Calixarenes 2001   Asfari Z. Böhmer V. Harrowfield J. Vicens J. Kluwer; Dordrecht: 2001. 

3 Compound 1 was synthesized according to a method previously described: Dyker G. Mastalerz M. Merz K. Eur. J. Org. Chem.  2003,  4355 

Suzuki-type cross-couplings with calix[4]arenes were previously described by:

4a Xu B. Miao Y.-J. Swager TM. J. Org. Chem.  1998,  63:  8561 

4b Larsen M. Krebs FC. Harrit N. Jørgensen M. J. Chem. Soc., Perkin Trans. 2  1999,  1749 

4c Wong MS. Xia PF. Lo PK. Sun XH. Wong WY. Shuang S. J. Org. Chem.  2006,  71:  940 

5 O-Alkylated halocalixarenes gave yields > 83% in the reaction with 2-biphenylboronic acid: Mastalerz M. PhD Thesis   Bochum; Germany: 2005. 

6 For a review on related oxidative arylation reactions see: Waldvogel SR. Mirk D. In Handbook of C-H Transformations   Wiley-VCH; Weinheim: 2005.  p.251-261  

7 Jaime C. de Mendoza J. Prados P. Nieto PM. Sãnchez C. J. Org. Chem.  1991,  56:  3372 

8 Plieninger H. Ege G. Ullah MI. Chem. Ber.  1963,  96:  1610 

9a Boden N. Bushby RJ. Cammidge AN. Headdock G. Synthesis  1995,  31 

9b Douadi T. Cariou M. Simonet J. Tetrahedron  1996,  52:  4449 

For other examples of spiro-annulated products from calix[4]arenes, see:

10a Litwak AM. Biali SE. J. Org. Chem.  1992,  57:  1943 

10b Litwak AM. Grynszpan F. Aleksiuk O. Cohen S. Biali SE. J. Org. Chem.  1993,  58:  393 

10c Aleksiuk O. Grynszpan F. Litwak AM. Biali SE. New. J. Chem.  1996,  20:  473 

10d Georghiou PE. Ashram M. Clase HJ. Brisdon JN. J. Org. Chem.  1998,  63:  1819 

11

Calixarene 2: To a solution of calixarene 1 (300 mg, 0.52 mmol) in 2-butanone (20 mL) NBS (1.135 g, 6.34 mmol) was added and the mixture was stirred for 20 h at r.t. An aq solution of Na₂S₂O₃ (20%, 20 mL) was added and the mix-ture was stirred for 20 min before the layers were separated. The organic layer was washed with H₂O (2 × 25 mL) and brine (25 mL), then dried over MgSO₄. The solvents were removed on a rotary evaporator to give 430 mg of an orange colored residue. After flash chromatography (PE-EtOAc, 2:1; R _f 0.26) and subsequent drying in vacuo (100 °C, 1 mbar), calixarene 2 was isolated as a colorless solid; yield: 230 mg (60%).
Mp 174 °C. IR (KBr): 3448, 3059, 2929, 1594, 1573, 1469, 1456, 1428, 1285, 1264, 1236, 1189, 1141, 1098, 1071, 990, 962, 914, 880, 858, 805, 776, 735 cm^-1. ¹H NMR (400.1 MHz, CDCl₃): δ = 3.39 (d, J = 14.0 Hz, 4 H), 3.96 (d, J = 13.5 Hz, 4 H), 6.95 (t, J = 7.5 Hz, 2 H), 7.01 (d, J = 7.0 Hz, 4 H), 7.09 (m, 4 H), 7.14 (s, 4 H), 7.85 (t, J = 6.8 Hz, 2 H, Py-4-H), 8.25 (d, J = 3.5 Hz, 2 H, Py-6-H). ¹³C NMR (100.6 MHz, CDCl₃): δ = 32.24 (t), 110.67 (d), 111.14 (s), 118.71 (d), 126.54 (d), 129.49 (d), 130.13 (d), 131.18 (s), 132.77 (s), 140.03 (d, Py-C-4), 147.32 (s), 147.81 (d, Py-C-6), 152.12 (s), 162.92 (s, Py-C-2). MS (FAB): m/z (%) = 737 (26)[M + H⁺]. UV/Vis (CH₃CN): λ_max (log ε) = 218 (4.6), 268 (3.9), 290 (sh, 3.7) nm. Anal. Calcd for C₃₈H₂₈Br₂N₂O₄·H₂O (754.48): C, 60.49; H, 4.01; N, 3.71. Found: C, 60.76; H, 3.79; N, 3.60.

12

Calixarene 3: To a solution of bromocalixarene 2 (220 mg, 0.30 mmol) and 2-biphenylboronic acid (225 mg, 1.136 mmol) in THF (10 mL) an aq solution of K₂CO₃ (2 N, 10 mL) and Pd(PPh₃)₄ (115 mg, 99 µmol) were added and the mixture was stirred at 120 °C under argon in a screw-capped flask for 20 h. The organic layer was washed with brine (25 mL) and dried over MgSO₄. THF was removed on a rotary evaporator to give 500 mg of a brown solid. After flash-chromatography (PE-EtOAc, 4:1; R _f 0.16) and subsequent drying in vacuo, calixarene 3 was isolated as a colorless solid; yield: 120 mg (46%).
Mp 145-160 °C. IR (KBr): 3448, 3050, 2925, 1593, 1468, 1457, 1428, 1320, 1280, 1237, 1183, 1142, 1083, 919, 876, 804, 762, 747, 701 cm^-1. ¹H NMR (400.1 MHz, CDCl₃): δ = 3.15 (d, J = 13.9 Hz, 4 H), 3.97 (d, J = 13.9 Hz, 4 H), 6.51 (d, J = 7.6 Hz, 4 H), 6.71 (s, 2 H), 6.77 (t, J = 7.6 Hz, 2 H), 6.86, (s, 4 H), 7.00 (ddd, ³ J = 7.0 Hz, ³ J = 5.0 Hz, ⁴ J = 0.8 Hz, 2 H, Py-5-H), 7.13 (d, J = 8.0 Hz, 2 H, Py-3-H), 7.15-7.23 (m, 10 H, biphenyl-H), 7.36-7.45 (m, 8 H, biphenyl-H), 7.74 (‘t’, J = 8.0 Hz, 2 H, Py-4-H), 8.19 (dd, J = 5.0 Hz, J = 1.8 Hz, 2 H, Py-6-H). ¹³C NMR (100.6 MHz, CDCl₃): δ = 31.59 (t), 110.41 (d, Py-C-3), 118.55 (d, Py-C-5), 126.08 (d), 126.12 (d), 126.98 (d), 127.40 (s), 127.91 (s), 128.00 (d), 129.12 (d), 129.89 (d), 130.38 (d), 130.42 (d), 130.63 (d), 132.55 (s), 132.84 (s), 139.75 (d, Py-C-4), 140.48, 140.53, 142.04 (s), 146.65 (s), 148.06 (d, Py-C-6), 151.81 (s), 163.62 (s, Py-C-2). MS (FAB): m/z (%) = 883.3 (100) [M + H⁺]. UV/Vis (CH₃CN): λ_max (log ε) = 224 (5.1), 238 (sh, 5.0), 268 (4.8), 284 (sh, 4.6) nm. Anal. Calcd for C₆₂H₄₆N₂O₄·H₂O (900.46): C, 82.63; H, 5.37; N, 3.11. Found: C, 82.52; H, 5.05; N, 2.79.

13

To a degassed solution of calixarene 3 (96 mg, 0.11 mmol) in anhyd CH₂Cl₂ (50 mL) a solution of FeCl₃ (465 mg, 2.87 mmol) in anhyd nitromethane (10 mL) was added dropwise over 5 min. A permanent stream of argon was bubbled through the solution. The reaction mixture was stirred for 40 min at r.t., MeOH (25 mL) was added and the volume of the solution was reduced to ca.10 mL. H₂O (25 mL) was added and the resulting precipitate was collected and washed with H₂O (3 × 10 mL). Flash chromatography (PE-EtOAc, 3:1; R _f 0.36) and recrystallization (CH₂Cl₂-i-PrOH) gave 60 mg (68%) of the spiro compound 4 as colorless needles.
Mp 253-255 °C. IR (KBr): 3060, 2923, 2854, 1667, 1647, 1597, 1585, 1570, 1470, 1458, 1428, 1395, 1355, 1287, 1271, 1250, 1191, 1142, 1096, 1081, 988, 940, 917, 885, 865, 801, 778, 759, 733, 645, 619 cm^-1. ¹H NMR (400.1 MHz, CDCl₃, 223 K): δ = 2.63 (d, J = 13.6 Hz, 2 H), 2.97 (d, J = 13.1 Hz, 2 H), 3.70 (d, J = 12.9 Hz, 2 H), 3.91 (d, J = 13.2 Hz, 2 H), 6.01 (d, J = 8.4 Hz, 2 H, Py-3-H), 6.30 (s, 2 H), 6.34 (s, 2 H), 6.71 (t, J = 5.5 Hz, 2 H, Py-4-H), 6.81 (d, J = 7.3 Hz, 2 H), 6.94 (t, J = 7.6 Hz, 2 H), 7.25 (t, J = 7.1 Hz, 3 H), 7.31 (m, 6 H), 7.39 (m, 1 H, Ar′H), 7.44 (m, 2 H), 7.57 (m, 2 H), 7.68 (t, J = 7.3 Hz, 1 H), 7.74 (t, J = 7.3 Hz, 1 H), 7.82 (d, J = 7.6 Hz, 1 H), 7.91 (m, 4 H), 7.98 (d, J = 7.3 Hz, 1 H), 9.18 (d, J = 7.6 Hz, 1 H). ¹³C NMR (100.6 MHz, CDCl₃, 223 K): δ = 29.70 (t), 35.07 (t), 56.00 (s, spiro-C), 56.67 (s, spiro-C), 110.57 (d, Py-C-3), 116.92 (d, Py-C-4), 119.99 (d), 120.44, 120.63, 120.83, 124.25 (d), 124.46 (d), 124.72 (s), 124.93 (d), 127.09 (d), 127.54 (d), 127.81 (d), 128.39 (d), 128.48 (s), 128.69 (s), 129.45 (s), 130.64 (d), 130.72 (s), 131.79 (s), 136.78 (s), 139.21 (d, Py-C-3), 140.10 (s), 140.48 (s), 140.98 (s), 141.20 (s), 141.71 (d), 141.99 (s), 143.45 (s), 143.95 (d), 144.67 (s), 147.27 (Py-C-6), 149.28 (s), 163.10 (s, Py-C-1), 183.23, 185.93 (s). MS (FAB): m/z (%) = 901.4 (20)[M + Na⁺]. UV/Vis (CH₃CN): λ_max (log ε) = 227 (4.9), 258 (4.6), 291 (4.0), 302 (4.1) nm. Anal. Calcd for C₆₂H₄₂N₂O₄·0.5H₂O (888.02): C, 83.86; H, 4.88; N, 3.15. Found: C, 83.64; H, 4.14; N, 2.96.