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

Abstract

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

Key words

[2,2]paracyclophanes - hydrogen transfer -

References and Notes

• 1 Brown CJ. Farthing AC. Nature (London)  1949,  164:  915 
• 2 Cram DJ. Steinberg H. J. Am. Chem. Soc.  1951,  73:  5691 
• 3 Vögtle F. Neumann P. Synthesis  1973,  85 
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• 5 Boekelheide V. Top. Curr. Chem.  1983,  113:  87 
• 6 Hopf H. Marquard C. In Strain and its Implications in Organic Chemistry   de Meijere A. Blechert S. Eds . Kluwer; Dordrech: 1983.  p.297 
• 7 Hopf H. Psiorz M. Chem. Ber.  1986,  119:  1836 
• 8 Werner C. Hopf H. Grunenberg J. Ernst L. Jones PG. Köhler F. Herges R. Eur. J. Org. Chem.  2009,  2621 
• For reviews, see:
• 9a Hopf H. Angew. Chem. Int. Ed.  2003,  42:  2822 ; Angew. Chem. 2003, 115, 2928
• 9b Hopf H. Bondarenko L. Ernst L. Jones PG. Grunenberg J. Hentschel S. Dix I. Greiving H. Chem. Eur. J.  2007,  13:  3950 
• 10 Birsa ML. Jones PG. Braverman S. Hopf H. Synlett  2005,  640 
• 11 Birsa ML. Hopf H. Synlett  2007,  2753 
• 12 Brown CJ. J. Chem. Soc.  1953,  3278 
• 13 Nicolau KC. Zuccarello G. Ogawa Y. Schweiger EJ. Kumazawa T. J. Am. Chem. Soc.  1988,  110:  4866 
• 14 Gleiter R. Ritter J. Angew. Chem. Int. Ed.  1994,  33:  2470 ; Angew. Chem. 1994, 106, 2550
• 15 Haberhauer G. Gleiter R. J. Am. Chem. Soc.  1999,  121:  4664 
• 16 Birsa ML. Jones PG. Hopf H. Eur. J. Org. Chem.  2005,  3263 
• 19 Hopf H. Wachholz G. Chem. Ber.  1987,  120:  1259 
• 20 Mallory FB. Mallory CW. Org. React.  1984,  30:  1 
• 21 Hopf H. Mlynek C. El-Tamany S. Ernst L. J. Am. Chem. Soc.  1985,  107:  6620 
• 22 Hopf H. Mlynek C. J. Org. Chem.  1990,  55:  1361 

17

Compound 1a: Yield: 1.2 g (83%); mp 210-211 ˚C. IR (ATR): 3240, 2922, 2223, 1482, 1261, 1005, 719 cm^-¹. ^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 × CH_Ar), 6.81 (m, 2 H, 2 × CH_Ar). ^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.

18

Compound 3b: Yield: 0.26 g (42%); mp 228-229 ˚C. IR (ATR): 2925, 1665, 1480, 1314, 1229, 1005, 767, 698 cm^-¹. ^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, CH_Ar), 6.55 (d, ⁴ J = 2.0 Hz, 1 H, CH_Ar), 6.64 (d, ^³ J = 7.9 Hz, 1 H, CH_Ar), 6.65 (dd, ^³ J = 7.7 Hz, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 6.80 (dd, ^³ J = 7.9 Hz, ⁴ J = 2.0 Hz, 1 H, CH_Ar), 7.06 (d, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 7.15-7.34 (m, 10 H, 10 × CH_Ar). ^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.

23

Compound 4: Yield: 0.1 g (23%); mp 142-143 ˚C. IR (ATR): 2927, 1663, 1485, 1434, 762, 730 cm^-¹. ^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, CH_Ar), 6.65 (d, ⁴ J = 2.0 Hz, 1 H, CH_Ar), 6.68 (dd, ^³ J = 8.2 Hz, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 6.70 (d, ^³ J = 8.2 Hz, 1 H, CH_Ar), 6.83 (dd, ^³ J = 8.0 Hz, ⁴ J = 2.0 Hz,
1 H, CH_Ar), 7.26 (d, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 7.7 (m, 4 H, 4 × CH_Ar), 8.22 (dd, ^³ J = 7.6 Hz, ⁴ J = 2.0 Hz, 1 H, CH_Ar), 8.39 (dd, ^³ J = 7.6 Hz, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 8.72 (dd, ^³ J = 8.0 Hz, ⁴ J = 1.9 Hz, 1 H, CH_Ar), 8.78 (dd, ^³ J = 8.0 Hz, ⁴ J = 2.0 Hz, 1 H, CH_Ar). ^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.