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Org. Synth. 2003, 80, 233

DOI: 10.15227/orgsyn.080.0233

HELICENEBISQUINONES: SYNTHESIS OF A [7]HELICENEBISQUINONE

[(Dinaphtho[2,1-c:1',2'-g]phenanthrene-1,4,15,18-tetrone, 9,10-dimethoxy-6,13-bis[[tris(1-methylethyl)silyl]oxy]-)]

Submitted by Kamil Paruch, Libor Vyklicky, and Thomas J. Katz¹.

Checked by Mitsuru Kitamura and Koichi Narasaka.

1. Procedure

A. 3,6-Bis[1-(triisopropylsiloxy)ethenyl]-9,10-dimethoxyphenanthrene. A solution of 8 g (0.025 mol) of 3,6-diacetyl-9,10-dimethoxyphenanthrene (Note 1) and 28 mL of triethylamine (Et₃N) (Note 2) in 80 mL of dry dichloromethane (CH₂Cl₂) (Note 2) is prepared under nitrogen in a 250-mL, round-bottomed flask equipped with a magnetic stir bar. The flask is cooled in an ice bath and 14 mL (0.052 mol) of triisopropylsilyl triflate (Note 3) is slowly added by syringe. The mixture is stirred for 15 min while cooling in the ice bath, then for 1 hr at ambient temperature. Hexane (200 mL) is added, and the organic phase is washed twice with 100-mL portions of 1M aqueous potassium hydroxide (KOH), dried quickly over potassium carbonate (K₂CO₃), and filtered. The solvent is removed, and the oily residue is dissolved in ca. 40 mL of hexane. The solution is poured onto a 4 × 4-cm plug of neutral alumina and washed with 200 mL of hexane. The solvent is removed and the residue is dried under vacuum (0.5 torr/80°C). 3,6-Bis[1-(triisopropylsiloxy)ethenyl]-9,10-dimethoxyphenanthrene (14.4 g, 91%) is obtained as a yellow oil (Notes 4, 5) and used in the subsequent step without further purification.

B. 6,13-Bis(triisopropylsiloxy)-9,10-dimethoxy[7]helicenebisquinone. A solution of the material obtained in Step A in 100 mL of heptane (Notes 6, 7) is added under nitrogen to a 500-mL, round-bottomed flask fitted with a reflux condenser. Thirty-four grams (0.31 mol) of 1,4-benzoquinone is added (Notes 8, 9), and the mixture is heated with an oil bath at 120°C for 3.5 days with stirring (Note 10). The reaction mixture is then cooled to 25°C and 25 mL of CH₂Cl₂ is added. The solids are broken into small pieces with the aid of a spatula, and the mixture is shaken for 15 min with 50 g of sand (Note 11). The supernatant liquid is decanted, the residue is extracted three times with 70-mL portions of 1:1 hexane:CH₂Cl₂, and the combined extracts are filtered through a pad of Celite. The solution is concentrated, and 1,4-benzoquinone is removed by sublimation by heating the residue to 100°C and applying a vacuum of ca. 0.5 torr. Methanol (MeOH, 100 mL) and ca. 20 g of sand are added, and the mixture is shaken until the solids are finely suspended (ca. 30 min). Water (20 mL) is added and the mixture is shaken for 10 min. The solids are collected by filtration and washed with ca. 250 mL of 5:1 MeOH:H₂O. The powder obtained after drying under vacuum at 100°C is dissolved in a small amount of toluene and purified by flash chromatography² on a 12 × 8-cm column of silica gel. A purple impurity is eluted with toluene, and the product is eluted with 1-3% tetrahydrofuran (THF) in toluene. After removal of the solvents and drying under vacuum at 100°C, 4.5 g of the helicenebisquinone (a 25% yield based on the enol ether, 22% based on 3,6-diacetyl-9,10-dimethoxyphenanthrene) is obtained as a dark red solid (Note 12).

2. Notes

1. Prepared according to the accompanying procedure (Paruch, K.; Vyklicky, L.; Katz, T. J. Org. Synth. 2003, 80, 227).

2. Dichloromethane and triethylamine were distilled from CaH₂.

3. Triisopropyl triflate (97%) was purchased from GSF Chemicals and used as received. The checkers purchased it from Tokyo Chemical Industry.

4. The product solidifies occasionally.

5. In two runs, the checkers obtained 15.8 and 15.2 g (99% and 98% yields). The product exhibits the following properties: ¹H NMR (CDCl₃, 400 MHz) δ: 1.18 (d, 36 H, J = 7.3), 1.35 (m, 6 H), 4.11 (s, 6 H), 4.57 (d, 2 H, J = 1.8), 5.06 (d, 2 H, J = 1.8), 7.90 (dd, 2 H, J = 8.6, 1.6), 8.17 (d, 2 H, J = 8.6), 8.96 (d, 2 H, J = 1.5); ¹³C NMR (CDCl₃, 75 MHz) δ: 12.8, 18.2, 61.0, 90.8, 119.5, 122.0, 124.3, 128.6, 129.1, 135.4, 144.1, 156.4; IR (CCl₄) cm⁻¹: 2946, 2868, 1607, 1464, 1322, 1292, 1113, 1015. The checkers reported the following elemental analysis. Calcd. for C₃₀H₅₈O₄Si₂: C, 71.87; H, 9.21. Found: C, 71.65; H, 9.20.

6. Heptane was distilled from sodium/benzophenone.

7. The yield is lower when toluene is used as solvent.

8. 1,4-Benzoquinone (98%, Aldrich) is purified by slurrying it in CH₂Cl₂ with two times its weight of basic alumina, filtering the mixture through Celite, concentrating the filtrate, and drying the residue under vacuum.

9. When seven molar equivalents of 1,4-benzoquinone are used, the yield drops to 12%.

10. Sometimes sublimation of 1,4-benzoquinone plugs the condenser, but turning off the cooling water ameliorates the problem.

11. The 20-30 mesh sand is obtained from Fisher Scientific.

12. In two runs the checkers obtained 8.4 and 8.5 g (40% and 42% yields). They found that the product can be purified further by recrystallization from MeOH/EtOAc; mp 272-274°C. IR (CCl₄) cm⁻¹: 2948, 2870, 1665, 1610, 1573, 1471, 1385, 1295, 1096. ¹H NMR (CDCl₃, 400 MHz) δ: 1.20 (d, 18 H, J = 7.5), 1.24 (d, 18 H, J = 7.5), 1.51 (m, 6 H), 4.21 (s, 6 H), 5.92 (d, 2 H, J = 10.1), 6.48 (d, 2 H, J = 10.1), 7.38 (s, 2 H), 8.40 (d, 2 H, J = 8.9), 8.46 (d, 2 H, J = 8.9); ¹³C NMR (CDCl₃, 75 MHz) δ: 13.0, 18.1, 61.2, 107.7, 121.1, 123.3, 125.0, 126.1, 128.0, 129.6, 129.9, 133.0, 134.1, 140.4, 145.3, 157.4, 183.6, 184.6. UV-vis (CH₃CN, c = 5.50 × 10⁻⁵ M): λ_max nm (log ε) 241 (4.54), 285 (4.48), 342 (4.18), 417 (3.76). Anal. Calcd for C₅₀H₅₈O₈Si₂: C, 71.22; H, 6.93. Found: C, 70.99; H, 6.87. The checkers obtained C, 71.20; H, 6.93.

Working with Hazardous Chemicals

The procedures in this article are intended for use only by persons with prior training in experimental organic chemistry. All hazardous materials should be handled using the standard procedures for work with chemicals described in references such as "Prudent Practices in the Laboratory" (The National Academies Press, Washington, D.C., 2011 www.nap.edu). All chemical waste should be disposed of in accordance with local regulations. For general guidelines for the management of chemical waste, see Chapter 8 of Prudent Practices.

These procedures must be conducted at one's own risk. Organic Syntheses, Inc., its Editors, and its Board of Directors do not warrant or guarantee the safety of individuals using these procedures and hereby disclaim any liability for any injuries or damages claimed to have resulted from or related in any way to the procedures herein.

3. Discussion

The procedure illustrates one that has been used to prepare significant quantities of a variety of helicenebisquinones.³ The majority of helicenes have been synthesized by photocyclization of derivatives of stilbene,⁴ but in most cases only small amounts can be prepared practically. Moreover, the functional groups that have been incorporated in these helicenes have not been generally useful. Using our procedure, helicenebisquinones having functional groups suitable for subsequent transformations can be prepared easily in significant amounts. Among the structures synthesized from these helicenes are helical polymers,⁵ helical discotic columnar aggregates^3e^,⁶ and liquid crystals,⁷ helical ligands,⁸ nonlinear optical materials,⁹ asymmetric catalysts,¹⁰ and substances that probe remote chirality.¹¹

Similar procedures have been used to prepare [7]helicenes that have different side chains,^3a,b [5]- and [6]carbohelicenes,^3c,d,e,g and [7]heterohelicenes.^3f,h

References and Notes

Department of Chemistry, Columbia University, New York, NY 10027.
Still, W. C.; Kahn, M.; Mitra, A. J. Org. Chem. 1978, 43, 2923.
(a) Fox, J. M.; Goldberg, N. R.; Katz, T. J. J. Org. Chem. 1998, 63, 7456; (b) Paruch, K.; Katz, T. J.; Incarvito, C.; Lam, K.-C.; Rhatigan, B.; Rheingold, A. L., J. Org. Chem. 2000, 65, 7602; (c) Katz, T. J.; Liu, L.; Willmore, N. D.; Fox, J. M.; Rheingold, A. L.; Shi, S.; Nuckolls, C.; Rickman, B. H. J. Am. Chem. Soc. 1997, 119, 10054; (d) Dreher, S. D.; Katz, T. J.; Lam, K.-C.; Rheingold, A. L. J. Org. Chem., 2000, 65, 815; (e) Nuckolls, C.; Katz, T. J.; Katz, G.; Collings, P. J.; Castellanos, L. J. Am. Chem. Soc. 1999, 121, 79; (f) Dreher, S. D.; Weix, D. J.; Katz, T. J. J. Org. Chem. 1999, 64, 3671; (g) Paruch, K.; Vyklicky, L.; Katz, T. J.; Incarvito, C. D.; Rheingold, A. L. J. Org. Chem. 2000, 65, 8774; (h) Phillips, K. E. S.; Katz, T. J.; Jockush, S.; Lovinger, A. J.; Turro, N. J. J. Am. Chem. Soc. 2001, 123, 11899.
(a) Laarhoven, W. H.; Prinsen, W. J. Top. Curr. Chem. 1984, 125, 63. (b) Mallory, F. B.; Mallory, C. W. Organic Reactions; Wiley: New York, 1984; Vol. 30, p. 1.
Dai, Y.; Katz, T. J. J. Org. Chem. 1997, 62, 1274.
(a) Lovinger, A. J.; Nuckolls, C.; Katz, T. J. J. Am. Chem. Soc. 1998, 120, 264; (b) Nuckolls, C.; Katz, T. J.; Verbiest, T.; Van Elshocht, S.; Kuball, H.-G.; Kiesewalter, S.; Lovinger, A. L.; Persoons, A. J. Am. Chem. Soc. 1998, 120, 8656; (c) Fox, J. M.; Katz, T. J.; Van Elshocht, S.; Verbiest, T.; Kauranen, M.; Persoons, A.; Thongpanchang, T.; Krauss, T.; Brus, L. J. Am. Chem. Soc. 1999, 121, 3453.
(a) Nuckolls, C.; Katz, T. J. J. Am. Chem. Soc. 1998, 120, 9541; (b) Nukolls, C,; Shao, R.; Jang, W.-G.; Clark, N. A.; Walba, D.; Katz, T. J. Chem. Mater. 2000, 14, 773.
Fox, J. M.; Katz, T. J. J. Org. Chem. 1999, 64, 302.
(a) Verbiest, T.; Van Elshocht, S.; Kauranen, M.; Hellemans, L.; Snauwaert, J.; Nuckolls, C.; Katz, T. J.; Persoons, A. Science (Washington, D. C.) 1998, 282, 913; (b) Busson, B.; Kauranen, M.; Nuckolls, C.; Katz, T. J. Persoons, A. Phys. Rev. Lett., 2000, 84, 79; (c) Verbiest, T.; Sioncke, S.; Persoons, A.; Vyklicky, L.; Katz, T. J. Angew. Chem. Int. Ed. 2002, 14, 3882.
Dreher, S. D.; Katz, T. J.; Lam, K.-C.; Rheingold, A. L. J. Org. Chem., 2000, 65, 815.
Weix, D. J.; Dreher, S. D.; Katz, T. J. J. Am. Chem. Soc. 2000, 122, 10027.

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

3,6-Diacetyl-9,10-dimethoxyphenanthrene:
Ethanone, 1,1'-(9,10-dimethoxy-3,6-phenanthrenediyl)bis- (9); (310899-08-2)

3,6-Bis[1-(triisopropylsiloxy)ethenyl]-9,10-dimethoxyphenanthrene:
Silane, [(9,10-dimethoxy-3,6-phenenthrenediyl)bis(ethenylideneoxy)]tris(1-methylethyl)- (9);
Triisopropyl triflate:
Methanesulfonic acid, trifluoro-, tris(1-methylethyl)silyl ester (9); (80522-42-5)

Triethylamine:
Ethanamine, N,N-diethyl- (9); (121-44-8)

1,4-Benzoquinone:
2,5-Cyclohexadiene-1,4-dione (9); (106-51-4)

6,13-Bis(triisopropylsiloxy)-9,10-dimethoxy[7]helicenebisquinone :
Dinaphtho [2,1-c:1',2'-g]phenanthrene-1,4,15,18-tetrone, 9,10-dimethoxy-6,13-bis[[tris(1-methylethyl)silyl]oxy]- (9); (310899-14-0)

Notes