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Anti-cyclooctadiene derivative 15:
1H NMR (600 MHz, CDCl3) δ 6.45 (dd, 2H, J1 = 1.84, J2 = 7.80 Hz), 6.41 (d, 2H, J = 1.84 Hz), 6.31 (d, 2H, J = 7.80 Hz), 6.05–6.00 (m, 2H), 5.94–5.88 (m, 2H), 4.89–4.82 (m, 2H), 3.39–3.29 (m, 2H), 3.19–3.09 (m, 2H), 3.06–2.96 (m, 2H), 2.92–2.83 (m, 2H), 2.78–2.68 (m, 2H), 2.34–2.26 (m, 2H) ppm;
13C NMR (150.9 MHz, CDCl3) δ 143.6, 140.2, 139.4, 136.6 (+), 132.9 (+), 131.4 (+), 130.7 (+), 128.8 (+), 48.5 (+), 36.3 (−), 33.3 (−), 27.2 (−) ppm;
MS (EI, 70 eV) m/z (%): 312 (19), 157 (33), 156 (40), 155 (100), 142 (12), 141 (55), 129 (18), 128 (22), 115 (17).
Interestingly, all three isomers of 10 (trans,trans-, cis,trans- and cis,cis-) under the above irradiation conditions furnish the same product: 16. It is hence likely that a rapid photoequilibration process precedes the ring closure to the final product.
Attempts to crystallize 14 from boiling ethanol led to a mixture of 14 and the cyclooctadiene derivative 15, which was separable by column chromatography. The divinylcyclobutane derivative 14 was completely converted into the cyclooctadiene derivative 15 within half an hour in boiling ethanol. The structure of 15 was confirmed by single-crystal X-ray analysis
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Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes
Henning Hopf1
, and Peter G. Jones2
, and Peter G. Jones2
1Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, Fax: +49 531 / 391 5388
2Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, Fax: +49 531 / 391 5387
2Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, Fax: +49 531 / 391 5387
Author email Corresponding author email
This article is part of the Thematic Series "Photocycloadditions and photorearrangements". Photoactive cyclophanes, part 6. For part 5 see [1].
Guest Editor: A. G. Griesbeck
Beilstein J. Org. Chem. 2011, 7, 658–667.
http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-7-78
p.jones@tu-bs.de, h.hopf@tu-bs.de
Braunschweig, Germany,
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