Synlett 2009(18): 3000-3002  
DOI: 10.1055/s-0029-1218286
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

A New Way to Generate Functionalized Bridges in [2,2]Cyclophanes

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

Publication History

Received 29 July 2009
Publication Date:
08 October 2009 (online)

Abstract

The synthesis of valuable precursors of cyclic endiynes has been accomplished by base-catalyzed intramolecular cyclization of pinacolone-type compounds.

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Compound 1a: Yield: 1.2 g (83%); mp 210-211 ˚C. IR (ATR): 3240, 2922, 2223, 1482, 1261, 1005, 719 cm. ¹H NMR (200 MHz, CDCl3, TMS): δ = 1.71 (d, 5 J = 3.4 Hz, 6 H, 2 × Me), 3.02 (m, 2 H, CH2), 3.09 (s, 4 H, 2 × CH2), 3.45 (m, 2 H, CH2), 4.05 (br s, 2 H, 2 × OH), 5.65 (q, 5 J = 3.4 Hz, 2 H, 2 × CH), 6.52 (m, 4 H, 4 × CHAr), 6.81 (m, 2 H, 2 × CHAr). ¹³C NMR (50 MHz, CDCl3, TMS): δ = 3.7 (q), 31.4 (t), 35.1 (t), 61.5 (d), 79.2 (s), 82.1 (s), 127.4 (d), 132.9 (d), 134.6 (s), 135.1 (d), 139.4 (s), 140.1 (s). MS (EI): m/z (%) = 326 (22)[M+ - H2O], 171 (15), 155 (100), 141 (38), 128 (35), 115 (30). Anal. Calcd for C24H24O2: C, 83.69; H, 7.02. Found: C, 83.76; H, 6.95.

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Compound 3b: Yield: 0.26 g (42%); mp 228-229 ˚C. IR (ATR): 2925, 1665, 1480, 1314, 1229, 1005, 767, 698 cm. ¹H NMR (400 MHz, CD2Cl2, TMS): δ = 2.75 (m, 1 H, CH2), 2.95 (m, 1 H, CH2), 2.98-3.30 (m, 4 H, 2 × CH2), 3.40 (m, 1 H, CH2), 3.95 (m, 1 H, CH2), 3.47 and 5.09 (ABq, ² J = 14.7 Hz, 2 H, CH 2CO), 6.46 (d, ³ J = 7.7 Hz, 1 H, CHAr), 6.55 (d, 4 J = 2.0 Hz, 1 H, CHAr), 6.64 (d, ³ J = 7.9 Hz, 1 H, CHAr), 6.65 (dd, ³ J = 7.7 Hz, 4 J = 1.9 Hz, 1 H, CHAr), 6.80 (dd, ³ J = 7.9 Hz, 4 J = 2.0 Hz, 1 H, CHAr), 7.06 (d, 4 J = 1.9 Hz, 1 H, CHAr), 7.15-7.34 (m, 10 H, 10 × CHAr). ¹³C NMR (100 MHz, CD2Cl2, TMS): δ = 32.4 (t), 34.0 (t), 34.9 (t), 35.2 (t), 48.7 (t), 99.4 (s), 101.0 (s), 122.2 (s), 126.2 (s), 127.5 (d), 127.6 (d), 128.2 (d, 2 C), 128.6 (d, 2 C), 129.3 (d, 2 C), 129.9 (d, 2 C), 131.1 (d), 132.9 (d), 133.4 (d), 135.2 (d), 137.0 (s), 138.0 (d), 138.3 (d), 139.1 (s), 139.5 (s), 139.9 (s), 140.1 (s), 142.4 (s), 142.5 (s), 150.6 (s), 201.5 (s). MS (EI): m/z (%) = 450 (100)[M+], 317 (32), 303 (35), 233 (98), 217 (95), 191 (18), 131 (28). Anal. Calcd for C34H26O: C, 90.63; H, 5.82. Found: C, 90.79; H, 5.75.

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Compound 4: Yield: 0.1 g (23%); mp 142-143 ˚C. IR (ATR): 2927, 1663, 1485, 1434, 762, 730 cm. ¹H NMR (400 MHz, CDCl3, TMS): δ = 2.77-3.15 (m, 4 H, 2 × CH2), 3.32 (m, 2 H, CH2), 3.55 (m, 1 H, CH2), 3.93 (m, 1 H, CH2), 4.57 and 5.26 (ABq, ² J = 15.6 Hz, 2 H, CH 2CO), 6.48 (d, ³ J = 8.0 Hz, 1 H, CHAr), 6.65 (d, 4 J = 2.0 Hz, 1 H, CHAr), 6.68 (dd, ³ J = 8.2 Hz, 4 J = 1.9 Hz, 1 H, CHAr), 6.70 (d, ³ J = 8.2 Hz, 1 H, CHAr), 6.83 (dd, ³ J = 8.0 Hz, 4 J = 2.0 Hz,
1 H, CHAr), 7.26 (d, 4 J = 1.9 Hz, 1 H, CHAr), 7.7 (m, 4 H, 4 × CHAr), 8.22 (dd, ³ J = 7.6 Hz, 4 J = 2.0 Hz, 1 H, CHAr), 8.39 (dd, ³ J = 7.6 Hz, 4 J = 1.9 Hz, 1 H, CHAr), 8.72 (dd, ³ J = 8.0 Hz, 4 J = 1.9 Hz, 1 H, CHAr), 8.78 (dd, ³ J = 8.0 Hz, 4 J = 2.0 Hz, 1 H, CHAr). ¹³C NMR (100 MHz, CD2Cl2, TMS): δ = 32.5 (t), 33.74 (t), 33.75 (t), 35.1 (t), 40.5 (t), 97.6 (s), 103.4 (s), 119.7 (s), 122.6 (d), 123.3 (d), 125.1 (d), 126.0 (s), 126.9 (d), 127.1 (d), 127.2 (d), 127.3 (d, 2 C), 129.5 (s), 130.1 (s), 130.6 (s), 131.1 (d), 132.0 (s), 132.9 (d), 133.1 (d), 135.0 (d), 137.8 (d), 137.9 (d), 138.9 (s), 139.0 (s), 139.4 (s), 140.2 (s), 142.1 (s), 142.4 (s), 200.9 (s). MS (EI): m/z (%) = 448 (100)[M+], 405 (24), 315 (43), 302 (25), 131 (18). Anal. Calcd for C34H24O: C, 91.04; H, 5.39. Found: C, 91.22; H, 5.27.