NOTE pubs.acs.org/joc
Two-Step Synthesis of Hexaammonium Triptycene: An Air-Stable Building Block for Condensation Reactions to Extended Triptycene Derivatives Michael Mastalerz,*,† Stefanie Sieste,† Mila Cenic,† and Iris M. Oppel‡ † ‡
Department of Organic Chemistry II & Advanced Materials, Ulm University, 89081 Ulm, Germany Department of Inorganic Chemistry, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany
bS Supporting Information ABSTRACT: A simple two-step synthesis of an air-stable hexaammoniumtriptycene is introduced, which can be used for a variety of transformations by condensation reactions, e.g., to benzimidazole, benzotriazole, and quinoxaline derivatives in high yields.
he D3h-symmetric triptycene (1)1 is a versatile molecular building block for the synthesis of larger molecules, which are frequently investigated in both supramolecular and materials chemistry.2 This is due to two facts: homoconjugation of the aromatic rings of the triptycene scaffold and molecular rigidity.3 The unique homoconjugation properties of the triptycene unit lead to “uncommon” properties, e.g., conductivity of conjugated polymers constructed thereof.4 For the construction of molecular motors and rotors,5 rotaxanes,6 shape-persistent macrocycles,7 and cages,8 as well as for metal organic frameworks,9 it is mainly the rigidity of the triptycene that is exploited on a molecular level. The rigidity and predefined geometry of triptycene is also the prerequisite of the formation of porous triptycene polymers.10 The 1,2-phenylenediamine unit is a very valuable synthetic moiety, which can be converted into a number of different functional groups, and the resulting molecules, such as metal salphens,11 quinoxalines,12 benzimidazoles,13 etc., bear interesting molecular as well as material properties. Therefore, efforts were made to use hexaminotriptycene 2 as a precursor for the synthesis of the corresponding quinoxaline derivatives,9a,14 rigid triptycene salphens with high internal free volumes,15 or D3hsymmetric trisphenanthroline derivatives.14b One major drawback of the hexamine 2 is the ease of oxidation,9a which occurs immediately after the synthetic reduction step from the corresponding nitro compound. Therefore, the hexamine has to be handled under exclusion of oxygen (or air) and needs to be used for subsequent reactions immediately after reduction of the precursor, which indicates that 2 does not allow storage of larger amounts. Another inconvenience is the five-step synthesis of
T
r 2011 American Chemical Society
hexaminotriptycene 2, starting from 1, with an overall yield of approximately 18% (Scheme 1, on the right).9a,16 All steps together are time-consuming, and some intermediates have to be purified via column chromatography, which is certainly a disadvantage on larger scales. Here, we present a simple two-step synthesis of hexaammoniumtriptycene hexachloride 4 (Scheme 1),17 an air-stable salt of the hexaminotriptycene 2. This hexaammonium salt can be stored on the bench for several weeks without precautions (exclusion of air, cooling, etc.) and can be used as a synthon for hexamine 2 for further transformations, giving high yields of products, which is demonstrated for some selected examples (see below). The two-step synthesis of the ammonium salt 4 starts with a 6-fold nitration of triptycene 1:18 Triptycene 1 was dissolved in fuming nitric acid and heated at 8085 °C for 4 h giving after workup a pale yellow solid as crude product. From 1H NMR spectroscopy it can be estimated that the desired hexanitrotriptycene 3 was formed as the main product in approximately 38% yield. By recrystallization from hot DMF we were able to separate 3 as yellow needles from the crude mixture in yields between 16 and 18% of sufficient purity (approximately 97% of the desired regioisomer as quantified by 1H NMR spectroscopy, see the Supporting Information). Differential scanning calometric (DSC, see Figure S16, Supporting Information) investigation of 3 3 DMF showed a minor broad endothermic peak between 87 and 117 °C, which corresponds to the melting point of the Received: April 27, 2011 Published: June 20, 2011 6389
dx.doi.org/10.1021/jo200843v | J. Org. Chem. 2011, 76, 6389–6393
The Journal of Organic Chemistry
NOTE
Scheme 1. Two-Step Synthesis of Air-Stable Hexaammoniumtriptycene Hexachloride 4 as a Synthetic Analogue of Hexaminotriptycene 2 (Right Side)a
Key: (a) fuming nitric acid, 85 °C, 4 h; (b) SnCl2 3 2H2O, EtOH, HClaq (conc), reflux, 17 h. The five-step synthesis of the previous route was in detail described in refs 9a and 16. a
compound (see the Experimental Section) accompanied by the loss of enclathrated DMF molecules. A further sharp and exothermic peak (384 kJ/mol) appears at 420 °C, which corresponds to combustion at that temperature. Caution! Although we never experienced any serious accidents with hexanitrotriptycene 3 on scales described within this article, we cannot exclude a spontaneous combustion of 3 on larger scales, e.g., by friction or shock, and therefore, the compound has to be treated as a potential safety hazard. We strongly recommend that adequate safety precautions be taken into account done when experiments are performed! The structure of 3 was additionally confirmed by single-crystal X-ray diffraction of suitable crystals obtained from DMF. Compound 3 crystallizes in the triclinic space group P-1 (see Figure S17 in the Supporting Information).19 The asymmetric unit contains one molecule 3 and one DMF molecule. The molecules themselves self-assemble in a hexagonal fashion, with DMF molecules enclathrated inside the framework voids. For the subsequent 6-fold transformation of the hexanitrotriptycene 3 to the corresponding hexaammonium hexachloride 4, we carried out the reduction using tin(II) chloride in aqueous hydrochloride/ethanol solution to give the pale-yellow ammonium salt 4 as a heptahydrate, as was determined by elemental analysis, in quantitative yield. We found this to be superior to methods using Pd/C and H2 or Raney-Ni/hydrazine. The reaction was performed under air, and no precautions were found to be necessary. More important to us than the high yield is the stability of 4 toward oxidation, which was known before for similar structures17 containing electron-rich o-phenylenediamine units.
This stability makes the handling for further transformations more convenient, which is exemplified in some selected condensation reactions (Scheme 2). For example, with triethyl orthoformate the benzimidazole analogue of triptycene (5a) is accessible in almost quantitative yield (98%)17 by using directly the ammonium salt 4 as reactant in water as solvent. Similarly, a benzotriazole analogue (5b) is accessible in 61% yield by reacting 4 with sodium nitrite and potassium acetate at room temperature.20 Quinoxaline derivative 6a can be prepared by reaction of the hexaammonium salt 4 with diethyloxalate in water at 100 °C, giving the product as a pale yellow solid in high yield (95%). For the reaction of 4 with anisil or dihydroxydioxane to the corresponding quinoxalines 6b and 6c the addition of stoichiometric amounts of potassium acetate is crucial: Treatment under similar conditions without potassium acetate gave no reactions while with potassium acetate quinoxaline 6b was accessible in 75%21 and quinoxaline 6c in almost quantitative yield (95%). As a last example to demonstrate the versatility of hexaammonium salt 4 in condensation reactions, the Schiff base condensation to a trinuclear nickel salphen (7) was tested. Trissalphen 7 is comparable to the compounds MacLachlan et al. reported and accessible in 68% yield as a wine-red solid.15 In summary, we have developed a facile two-step synthesis of hexaammoniumtriptycene hexachloride 4 that is air-stable and can be stored on the bench for several weeks without special precautions (e.g., excluding air, light etc.). An additional advantage is that for the purification of both compounds, 3 and 4, no column chromatography is needed. Compound 4 can be used as 6390
dx.doi.org/10.1021/jo200843v |J. Org. Chem. 2011, 76, 6389–6393
The Journal of Organic Chemistry
NOTE
Scheme 2. Reactions of Hexaammonium Salt 4 in Various Condensation Reactionsa
a Key: (a) CH(OEt)3, DMF, CH2Cl2, rt, 22h, 98% of 5a; (b) KOAc, NaNO2, H2O, rt, 16h, 61% of 5b; (c) diethyl oxalate, H2O, 100 °C, 20 h, 95% of 6a; (d) KOAc, 2,3-dihydroxydioxane, THF, rt, 19 h, 75% of 6b; (e) anisil, KOAc, EtOH, 100 °C, 3 d, 95% of 6c; (f) 3,5-di-tert-butylsalicylaldehyde, Ni(OAc)2 3 4H2O, KOAc, 16 h, 90 °C, 68% of 7.
precursor for a variety of condensation reactions, resulting in a number of functionalized extended triptycene derivatives in high yields. With air-stable hexaammonium salt 4 we are providing a precursor that will serve as versatile building block for the synthesis of larger molecules and new materials based on D3hsymmetric subunits. This synthetic approach will be adopted for similar compounds containing electron-rich o-phenylenediamine subunits, which are prone to fast oxidation, such as tribenzotriquinacene22 or centrohexaindane derivatives.23
’ EXPERIMENTAL SECTION 2,3,6,7,14,15-Hexanitrotriptycene (3). Triptycene (5.15 g, 20.2 mol) was suspended in fuming nitric acid (150 mL, 100%) and heated to 85 °C for 4 h. The reaction mixture was cooled to room temperature, poured into water (1 L), and stirred for 1 h. The pale yellow (slightly pink) precipitate was collected by suction filtration, washed with water, and dried in air to give approximately 11 g of crude product. Recrystallization from hot DMF (reflux temperature) gives after cooling to room temperature 3 as yellow crystals (1.85 g, 18%): mp 113 °C; 1H NMR (400 MHz, DMSO-d6) δ 8.43 (s, 6H), 6.68 (s, 2H); 13C NMR (100 MHz, DMSO-d6) δ 147.9, 140.2, 122.6, 50.7; FT-IR (KBr): 3090, 3044, 2886, 1539, 1459, 1408, 1368, 1345, 1253, 1206, 1167, 913, 884, 860, 781, 758, 581, 533 cm1; UV/vis (CH3CN) λmax (log ε) 193 nm (2.1), 230 (2.0), 274, sh (1.6); MS (CI) m/z 553 (M + C2H5+), 526
(M + 2+), 525 (M + H+). Anal. Calcd for C20H8N6O12 3 DMF (597.40): C, 46.24; H, 2.53; N, 16.41. Found: C, 46.20; H, 2.67; N, 16.59.
2,3,6,7,14,15-Hexaammoniumtriptycene Hexachloride (4). A suspension of 3 (1.25 g, 2.4 mmol) and tin(II) chloride dihydrate (18 g, 79 mmol) in ethanol (140 mL) and concentrated hydrochloric acid (60 mL) was refluxed for 24 h. The reaction mixture was cooled to room temperature and the white precipitate collected by filtration, washed with concd hydrochloric acid (3 15 mL), and dried in vacuum to give 4 3 7H2O as a pale yellow solid (1.70 g (quant): mp 288 °C dec;24 1 H NMR (400 MHz, DMSO-d6) δ 7.11 (s, 6H), 5.38 (s, 2H); 13C NMR (126 MHz, DMSO-d6) δ 141.9, 125.6, 117.9, 50.3. FT-IR (KBr) 3401, 2856, 2567, 1627, 1556, 1478, 1278, 1205, 1092, 885, 829, 587, 457, 229 cm1. Anal. Calcd for C20H26N6Cl6 3 7H2O (689.2): C, 34.85; H, 5.85; N, 12.19. Found: C, 34.65; H, 5.60; N, 11.83.
2,6,12-Trihydrotripty[2,3-d:6,7-d0 :12,13-d00 ]triimidazole (5a).25
To a suspension of hexammonium salt 4 3 7H2O (600 mg, 0.44 mmol) in DMF (10 mL) and dichloromethane (25 mL) was added triethyl orthoformate (2 mL) and the mixture stirred for 22 h at room temperature. To the creamy yellow solution were added methanol (50 mL) and triethylamine (8 mL), resulting in a green solution. Solvents were removed by rotary evaporation until a yellow solid started to precipitate. Water was added in large excess and the yellow precipitate collected by suction filtration, washed with water (3 30 mL), and dried in vacuo to give 5a as an off-white solid (321 mg, 98%): mp >400 °C; 1H NMR (500 MHz, DMSO-d6) δ 8.13 (s, 3H), 7.62 (s, 6H), 5.75 (s, 2H), 13 C NMR (126 MHz, 375 K, DMSO-d6) δ 140.7, 139.9, 134.9, 109.7, 6391
dx.doi.org/10.1021/jo200843v |J. Org. Chem. 2011, 76, 6389–6393
The Journal of Organic Chemistry 53.0; FT-IR (KBr) 3614, 3109, 2949, 2809, 1719, 1628, 1580, 1500, 1474, 1449, 1406, 1361,1309, 1293, 1266, 1235, 1186, 1061, 1037, 1021, 953, 754, 623, 587, 455, 436, 411 cm1; UV/vis (MeOH) λmax (log ε) 243 nm (0.9), 250,sh (0.9), 260,sh (0.7), 271, sh (0.3), 291 (1.1), 301 (1.2); HRMS (ESI) m/z calcd for C20H14N6Na 397.11722, found 397.11649.
2,6,12-Trihydrotripty[2,3-d:6,7-d0 :12,13-d00 ]triazole (5b).25
Hexaammonium salt 4 3 7H2O (140 mg, 0.1 mmol) and potassium acetate (120 mg, 0.6 mmol) were dissolved in water (4 mL), and a solution of sodium nitrite (55 mg, 0.8 mmol, in 1 mL water) was added dropwise at room temperature. Immediately, a tan solid started to precipitate. After the reaction mixture was stirred for another 16 h at room temperature, the precipitate was collected on a B€uchner funnel and washed with water (3 4 mL). After drying in vacuo, 5b remained as pale tan solid (46 mg, 61%): mp >400 °C; 1H NMR (400 MHz, DMSO-d6) δ 15.57 (s, br, 3H), 8.09 (s, br, 3H), 7.87(s, br, 3H), 6.08 (s, br, 2H); 13C NMR (100 MHz, DMSO-d6) δ 143.4 (br), 142.6, 140.0 (br),131.6, 113.4, 106.2, 52.2; FT-IR (KBr): 3388, 3161, 2985, 2905, 2796, 1630, 1587, 1506, 1446, 1389, 1293, 1267, 1243, 1195, 1078, 995, 882, 754, 587, 454, 404 cm1; UV/vis (DMF) λmax (log ε) 294 nm (1.4), 303 (1.4); HRMS (ESI) m/z calcd for C20H11N9 378.12102, found 378.12101.
2,3,6,7,12,13-Hexahydroxy-2,6,12-trihydrotripty[2,3-d:6,7-d0 : 12,13-d00 ]tripyrazyl (6a):25. Hexaammonium salt 4 3 7H2O (140 mg,
0.19 mmol) and diethyl oxalate (0.1 mL) were dissolved in water (6 mL) and vigorously stirred at 100 °C. After 20 h, the reaction mixture was cooled to room temperature and the off-white solid collected on a B€uchner funnel and washed with water (3 4 mL). After being dried in vacuo, 6a remained as an off-white solid (105 mg, 95%): mp >400 °C; 1 H NMR (500 MHz, DMSO-d6) δ 11.88 (s, 6H), 7.17 (s, 6H), 5.71 (s, 2H); 13C NMR (126 MHz, 375 K, DMSO-d6) δ 155.2, 139.9, 122.3, 110.7, 50.1; FT-IR (KBr) 3443, 3177, 3060, 2952, 1689, 1481, 1454, 1390, 1303, 1245, 1193, 1095, 890, 795, 646, 537, 462 cm1; UV/vis (DMF) λmax (log ε) 329 nm (1.0), 341 (1.0), 356,sh (0.8); HRMS (ESI) m/z calcd for C26H14N6O6Na 529.08670, found 529.08606.
2,6,12-Trihydrotripty[2,3-d:6,7-d0 :12,13-d00 ]tripyrazyl (6b).25
Hexaammonium salt 4 3 7H2O (155 mg, 0.22 mmol), potassium acetate (140 mg, 1.4 mmol), and 2,3-dihydroxydioxane (90 mg, 0.75 mmol) were suspended in THF (6 mL) and stirred at room temperature for 19 h. The reaction mixture was filtered through a plug of silica and washed with THF. Solvent was removed at the rotary evaporator to obtain 230 mg of a pale yellow solid. The solid was digested in 15 mL of light petroleum ether, filtered, and washed with petroleum ether (3 5 mL). The residue was dried in vacuo to give 6b as a pale yellow solid (67 mg, 75%): mp >400 °C; 1 H NMR (400 MHz, CDCl3) δ 8.78 (s, 6H), 8.23 (s, 6H), 6.15 (s, 2H). Analytical data are in accordance to those previous reported.9a,14a
2,3,6,7,12,13-Hexa(40 -methoxyphenyl)-2,6,12-trihydrotripty[2,3-d:6,7-d0 :12,13-d00 ]tripyrazyl (6c).25 In a screw-capped vial hex-
aammonium salt 4 3 7H2O (67 mg, 0.097 mmol), anisil (90 mg, 0.33 mmol), and potassium acetate (60 mg, 0.61 mmol) were suspended in 6 mL of ethanol, and the mixture was heated to 100 °C for three days. After the mixture was cooled to room temperature, the yellow precipitate was collected on a Buchner funnel, washed with methanol (3 4 mL), and dried in vacuo. The remaining solid was purified by column chromatography (SiO2, ethyl acetate/light petroleum ether 3:1 v/v) to give, after removal of solvent and subsequent drying in vacuum, 6c as a yellow solid (96 mg, 95%): mp 252255 °C; 1H NMR (500 MHz, CDCl3) δ 8.21 (s, 6H), 7.44 (d, J = 8.8 Hz, 12H), 6.84 (d, J = 8.8 Hz, 12H), 6.05 (s, 2H), 3.81 (s, 18H); 13C NMR (101 MHz, CDCl3) δ 160.1, 152.8, 143.7, 140.2, 131.6, 131.2, 123.6, 113.7, 55.3, 53.2; FT-IR (KBr) 2928, 2834, 1607, 1577, 1514, 1452, 1351, 1295, 1252, 1175, 1110, 1096, 1059, 1029, 892, 834, 762, 735, 695, 659, 602, 565, 496, 412 cm1; UV/vis (CH2Cl2) λmax (log ε) 261 nm (2.2), 281 sh, (2.1), 385 (1.7); MS (MALDI-TOF) m/z 1048 (M+). Anal. Calcd for C68H50N6O6 (1047.16): C, 77.99; H, 4.81; N, 8.03. Found: C, 77.74; H, 5.04; N, 8.09.
NOTE
Tris-nickelsalphen 7. In a screw-capped vial, hexaammonium salt 4 (50 mg, 0.072 mmol), salicylaldehyde (130 mg, 0.55 mmol), nickel acetate tetrahydrate (60 mg, 0.21 mmol), and potassium acetate (60 mg, 0.66 mol) were suspended in 6 mL of ethanol and the mixture heated for 16 h at 90 °C. After the mixture was cooled to room temperature, the wine-red precipitate was collected on a B€uchner funnel, washed with ethanol (3 2 mL), and dried in the vacuum stream to obtain 7 as a wine-red solid (123 mg, 68%): mp >400 °C; 1H NMR (500 MHz, DMSO-d6, 375 K) δ 8.62 (s, 6H), 8.24 (s, 6H), 7.37 (s, 6H), 5.75 (s, 2H), 1.41 (s, 54H), 1.33 (s, 54H). FT-IR (KBr) 2956, 2906, 2868, 1618, 1586, 1525, 1467, 1426, 1385, 1358, 1331, 1269, 1251, 1234, 1199, 1178, 1129, 1058, 1026, 938, 910, 864, 840, 788, 751, 676, 636, 574, 541, 506 cm1; UV/vis (DMF) λmax (log ε) 386 nm (2.0), 405,sh (1.9), 493 (1.6); HRMS (ESI) m/z calcd for C110H1134N6O6Ni3 1808.84198, found 1808.84155. Anal. Calcd for C110H134N6O6Ni3: C, 61.74; H, 6.49. Found: C, 61.61; H, 6.23.
’ ASSOCIATED CONTENT
bS
H and 13C NMR spectra of all new compounds. MALDI-TOF MS spectra of 7 and crystallographic data of 3. This material is available free of charge via the Internet at http://pubs.acs.org. Supporting Information.
1
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT The “Fond der Chemischen Industrie (FCI)” and the “Deutsche Forschungsgemeinschaft (DFG, Project MA4061/4-1)” are gratefully acknowledged for financial support. We also thank the German Academic Exchange Sevice (DAAD) for a scholarship for M.C. in the frame of the IASTE-program (D/10/1068/1). Solvay Fluor GmbH is acknowledged for the donation of chemicals. M.M. thanks Prof. T. M. Klap€otke (LMU Munich) for helpful discussions. ’ REFERENCES (1) Bartlett, P. D.; Ryan, M. J.; Cohen, S. G. J. Am. Chem. Soc. 1942, 64, 2649–2653. (2) (a) Chong, J. H.; MacLachlan, M. J. Chem. Soc. Rev. 2009, 38, 3301–3315. (b) Zhao, L.; Li, Z.; Wirth, T. Chem. Lett. 2010, 39, 658–668. (3) Harada, N.; Uda, H. J. Chem. Soc., Perkin Trans. 2 1989, 1449–1453. (4) (a) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998, 120, 5321–5322. (b) Zhao, D.; Swager, T. M. Org. Lett. 2005, 7, 4357–4360. (c) Zhu, Z.; Swager, T. M. Org. Lett. 2001, 3, 3471–3474. (d) Long, T. M.; Swager, T. M. J. Am. Chem. Soc. 2003, 125, 14113–14119. (e) Perepichka, D. F.; Bendikov, M.; Meng, H.; Wudl, F. J. Am. Chem. Soc. 2003, 125, 10190–10191. (5) Kelly, T. R.; Cai, X.; Damkaci, F.; Panicker, S. B.; Tu, B.; Bushell, S. M.; Cornella, I.; Pigott, M. J.; Salives, R.; Cavero, M.; Zhao, Y.; Jasmin, S. J. Am. Chem. Soc. 2007, 129, 376–386. (6) See, for instance: Zhou, X.-Z.; Chen, C.-F. J. Am. Chem. Soc. 2005, 127, 13158–13159. (7) For a review covering macrocycles based on triptycenes, see: Chen, C.-F. Chem. Commun. 2011, 47, 1674–1688. (8) (a) Mastalerz, M. Chem. Commun. 2008, 4756–4758. (b) Mastalerz, M.; Schneider, M. W.; Oppel, I. M.; Presly, O. Angew. Chem., Int. Ed. 2011, 50, 1046–1051. (9) (a) Chong, J. H.; MacLachlan, M. J. Inorg. Chem. 2006, 45, 1442–1444. (b) Vagin, S.; Ott, A.; Weiss, H.-C.; Karbach, A.; Volkmer, D.; 6392
dx.doi.org/10.1021/jo200843v |J. Org. Chem. 2011, 76, 6389–6393
The Journal of Organic Chemistry
NOTE
Rieger, B. Eur. J. Inorg. Chem. 2008, 2601–2609. (c) Vagin, S. I.; Ott, A. K.; Hofmann, S. D.; Lanziger, D.; Rieger, B. Chem.—Eur. J. 2009, 15, 5845–5853. (10) (a) Ghanem, B. S.; Msayib, K. J.; McKeown, N. B.; Harris, K. D. M.; Pan, Z.; Budd, P. M.; Butler, A.; Selbie, J.; Book, D.; Walton, A. Chem. Commun. 2007, 67–68. (b) Ghanem, B. S.; Hashem, M.; Harris, K. D. M.; Msayib, K. J.; Xu, M. C.; Budd, P. M.; Chaukura, N.; Book, D.; Tedds, S.; Walton, A.; McKeown, N. B. Macromolecules 2010, 43, 5287– 5294. (11) For reviews, see: (a) Wezenberg, S. J.; Kleij, A. W. Angew. Chem., Int. Ed. 2008, 47, 2354–2364. (b) Kleij, A. W. Chem.—Eur. J. 2008, 14, 10520–10529. (12) For a review on N-hetarenes, including quinoxalines, see: Bunz, U. H. F. Chem.—Eur. J. 2009, 15, 6780–6789. (13) Preston, P. N. Chem. Rev. 1974, 74, 279–314. (14) (a) Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683–8690. (b) Jiang, Y.; Chen, C.-F. Synlett 2010, 11, 1679–1681. (15) Chong, J. H.; Ardakani, S. J.; Smith, K. J.; MacLachlan, M. J. Chem.—Eur. J. 2009, 15, 11824–11828. (16) (a) Shalaev, V. K.; Getmanova, E. V.; Skvarchenko, V. R. Zh. Org. Khim. 1976, 12, 191–197. (17) A similar octaammonium chloride salt derivative of a cavitand was synthesized in a similar fashion: Far, A. R.; Shivanyuk, A.; Rebek, J., Jr. J. Am. Chem. Soc. 2002, 124, 2854–2855. (18) The synthesis of hexanitrotriptycene 3 from further nitration of a regioisomeric mixture of trinitrotriptycenes on small scale was previous described by: Shalaev, V. K.; Skvarchenko, V. R. Vestn. Mosk. Univ. Ser. 2: Khim 1974, 15, 726–730. (19) Data were collected on an Oxford Diffraction Saphire II (Mo radiation, graphite monochromator). The structure was solved by direct methods and refined by full-matrix least-squares methods using SHELXTL-97.26 All non-hydrogen atoms were refined using anisotropic thermal parameters. X-ray data have been deposited at the Cambridge Crystallographic Data Centre (CCDC-822707). Crystal Data for 2: T = 110(2) K, C23H15N7O13, M = 597.42, triclinic space group P-1, a = 9.7248(3) Å, b = 10.2761(3) Å, c = 13.0872(3) Å, R = 92.220(2)°, β = 109.872(3)°, γ = 97.000(3)° V = 1216.29(6) Å3, Z = 2, DC = 1.631 g/ cm3, μ = 0.137 mm1, 3.16° < Θ < 26.25°, reflections collected/unique 29500/4902 [R(int) = 0.0295], data/restrains/parameters 4902/0/390, GOF 1.049, final R[xI > 2σ(I)] R1 = 0.0395, wR2 (all data) = 0.1069, residual density 0.475 and 0.265 e 3 A3. (20) Damshoder, R. E.; Peterson, W. D. Org. Synth. 1940, 20, 16–18. (21) Note that with the free, air-sensitive hexamine 2 product 6b was isolated in 29% yields (ref 9a). (22) Tellenbr€ocker, J.; Kuck, D. Angew. Chem., Int. Ed. 1999, 111, 919–922. (23) For a review of centropolyindanes, see: Kuck, D. Chem. Rev. 2006, 106, 4885–4925. (24) The compound starts to darken at 260 °C, so we assume that decomposition starts already at this temperature. (25) The IUPAC names for the compounds are as follows: 5a: 5,7,15,17,24,26-hexaazaoctacyclo[9.9.9.0{2,10}.0{4,8}.0{12,20}.0{14,18}.0{21,29}. 0{23,27}]nonacosa-2,4(8),5,9,12,14(18),15,19,21(29),22,24,27-dodecaene. 5b: 5,6,7,15,16,17,24,25,26-nonaazaoctacyclo[9.9.9.0{2,10}.0{4,8}.0{12,20}. 0{14,18}.0{21,29}.0{23,27}]nonacosa-2,4(8),5,9,12,14(18),15,19,21(29),22,24,27dodecaene. 6a: 6,7,17,18,27,28-hexahydroxy-5,8,16,19,26,29-octaazaoctacyclo[10.10.10.0{2,11}.0{4,9}.0{13,22}.0{15,20}.0{23,32}.0{25,30}]dotriacosa2,4(9),5,7,10,13,15(20),16,18,21,23(32),24,26,28,30-pentadecaene. 6b: 5,8,16,19,26,29-octaazaocta-cyclo[10.10.10.0{2,11}.0{4,9}.0{13,22}.0{15,20}. 0{23,32}.0{25,30}]dotriacosa-2,4(9),5,7,10,13,15(20),16,18,21,23(32),24,26,28,30pentadecaene. 6c: 6,7,17,18,27,28-hexa(4-methoxyphenyl)-5,8,16,19,26,29octaazaoctacyclo[10.10.10.0{2,11}.0{4,9}.0{13,22}.0{15,20}.0{23,32}.0{25,30}]dotriacosa-2,4(9),5,7,10,13,15(20),16,18,21,23(32),24,26,28,30-pentadecaene. (26) Sheldrick, G. M. SHELXTL-97, Universit€at G€ottingen, G€ottingen, Germany, 1997.
6393
dx.doi.org/10.1021/jo200843v |J. Org. Chem. 2011, 76, 6389–6393
