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Synlett 2011(2): 259-261  
DOI: 10.1055/s-0030-1259088
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Orthogonal π-Bridges in [2.2]Paracyclophanes

M. Lucian Birsa*a,b, Peter G. Jonesc, Henning Hopfb
a Department of Organic Chemistry, ‘Al. I. Cuza’ University of Iasi, 11 Carol I, 700506 Iasi, Romania
b Institute of Organic Chemistry, Technical University of Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
Fax: +40(232)201313; e-Mail: lbirsa@uaic.ro;
c Institute of Inorganic and Analytical Chemistry, Technical University of Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
Further Information

Publication History

Received 20 October 2010
Publication Date:
07 December 2010 (online)

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Abstract

Orthogonal π-bridges have been introduced into [2.2]paracyclophanes by the reaction of the pseudo-geminal bisacetylene with various monoacetylenes and nitriles. The reactions with bistrimethylsilylacetylene and dimethylacetylenedicarboxylate take place even in the absence of a catalyst. This procedure can incorporate not only aromatic but also heteroaromatic bridges, as in pyridine-annulated cyclophane.

Key words

[2.2]paracyclophane - cyclotrimerization - acetylenes - nitriles - aromatic bridges

    References and Notes

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  • 19a

    Crystal Structure Determination of 3a - Crystal Data
    Orthorhombic, space group P212121, a = 11.9328 (11), b = 12.6273 (12), c = 15.8769 (15) Å, Z = 4, T = 100 K.
    Data Collection
    A crystal ca. 0.3 × 0.2 × 0.17 mm³ was used to record 89806 intensities to 2θ 63˚ on a Bruker APEX-2 diffractometer using Mo Kα radiation (λ = 0.71073 Å).
    Structure Refinement
    The structure was refined anisotropically on F ² (program SHELXL-97)¹7b to wR2 = 0.0861, R1 = 0.0320 for 277 parameters and 7929 unique reflexions. Data have been deposited in Cambridge under the number CCDC-796776.

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Typical Procedure for Cyclotrimerization
To a boiling solution of xylene (30 mL) a solution of bisacetylene 1 (0.5 mmol), acetylene 2a-c (2.5 mmol), and CpCo(CO)2 (5 mol%) in xylene (20 mL) was added with a syringe pump over 16 h. The solvent was evaporated under vacuum, and the residue purified by column chromatography on silica gel.

17

Analytical Data of Compound 3a Yield 134 mg (63%); mp 158-159 ˚C. IR (ATR): 3342, 1611, 1432, 1342, 1297, 1031, 771, 755 cm-¹. ¹H NMR (400 MHz, CDCl3, TMS): δ = 0.36 (s, 18 H, 6 CH3), 2.47 (m, 2 H, CH2), 2.51 (m, 2 H, CH2), 2.95 (m, 4 H, 2 CH2), 6.24 (d, 2 H, 4 J = 2.0 Hz, 2 CHar), 6.33 (d, 2 H, ³ J = 7.9 Hz, 2 CHar), 6.42 (dd, 2 H, ³ J = 7.9 Hz, 4 J = 2.0 Hz, 2 CHar), 7.74 (s, 2 H, 2 CHar). ¹³C NMR (100 MHz, CDCl3, TMS): δ = 2.2 (q), 33.5 (t), 35.4 (t), 130.5 (d), 130.8 (d), 132.8 (d), 139.1 (d), 139.3 (s), 141.0 (s), 143.6 (s), 144.8 (s), 145.1 (s). MS (EI): m/z (%) = 426 (100)[M+], 398 (81), 338 (41), 279 (34), 184 (22), 167 (23), 149 (40). Anal. Calcd for C28H34Si2: C, 78.81; H, 8.03. Found: C, 78.52; H, 7.89.

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Analytical Data of Compound 3b Yield 145 mg (73%); mp 162-163 ˚C. IR (ATR): 2927, 1719, 1438, 1325, 1262, 1243, 1120, 1066, 952, 783, 614 cm-¹. ¹H NMR (200 MHz, CDCl3, TMS): δ = 2.52 (m, 4 H, 2 CH2), 3.05 (m, 4 H, 2 CH2), 3.95 (s, 6 H, 2 CH3), 6.20 (d, 2 H, 4 J = 2.0 Hz, 2 CHar), 6.39 (d, 2 H, ³ J = 8.0 Hz, 2 CHar), 6.52 (dd, 2 H, ³ J = 8.0 Hz, 4 J = 2.0 Hz, 2 CHar), 7.89 (s, 2 H, 2 CHar). ¹³C NMR (50 MHz, CDCl3, TMS): δ = 33.1 (t), 35.4 (t), 52.7 (q), 124.9 (d), 130.9 (s), 131.5 (d), 133.1 (d), 138.5 (d), 139.6 (s), 140.1 (s), 141.8 (s), 149.3 (s), 168.1 (s). MS (EI): m/z (%) = 398 (100)[M+], 370 (60), 339 (35), 279 (39), 265 (32), 252 (23). Anal. Calcd for C26H22O4: C, 78.39; H, 5.52. Found: C, 78.61; H, 5.41.

20

Analytical Data of Compound 5a Yield 58 mg (29%); mp 133-134 ˚C. IR (ATR): 2930, 1595, 1517, 1460, 1336, 1317, 1105, 855, 721 cm-¹. ¹H NMR (600 MHz, CDCl3, TMS): δ = 2.61-2.80 (m, 4 H, 2 CH2), 3.03-3.13 (m, 4 H, 2 CH2), 2.95 (m, 4 H, 2 CH2), 6.26 (d, 1 H, 4 J = 1.9 Hz, CHar), 6.29 (d, 1 H, 4 J = 1.9 Hz, CHar), 6.46 (d, 1 H, ³ J = 8.1 Hz, CHar), 6.48 (d, 1 H, ³ J = 8.1 Hz, CHar), 6.57 (dd, 1 H, ³ J = 8.1 Hz, 4 J = 1.9 Hz, CHar), 6.59 (dd, 1 H, ³ J = 8.1 Hz, 4 J = 1.9 Hz, CHar), 8.03 (s, 1 H, CHar), 8.31 (d, 2 H, ³ J = 8.0 Hz, 2 CHar), 8.39 (d, 2 H, ³ J = 8.0 Hz, 2 CHar), 8.89 (s, 1 H, CHar). ¹³C NMR (150 MHz, CDCl3, TMS): δ = 33.0 (t), 33.3 (t), 35.3 (t), 35.4 (t), 117.1 (d), 124.1 (d), 127.8 (d), 131.7 (d), 131.8 (d), 133.3 (d), 133.5 (d), 137.7 (d), 139.2 (d), 139.6 (s), 139.7 (s), 140.0 (s), 140.3 (s), 140.5 (s), 141.3 (s), 141.9 (s), 144.9 (d), 145.3 (s), 148.2 (s), 154.1 (s), 155.9 (s). MS (EI): m/z (%) = 404 (100)[M+], 389 (15), 359 (45), 283 (12), 190 (86), 176 (31). Anal. Calcd for C27H20N2O2: C, 80.20; H, 4.95. Found: C, 80.34; H, 4.79.