Svjetlom do heteropolicikličkih spojeva; Reakcije supstituiranih furostilbena
Synthetic organic photochemistry, the chemistry of excited states of a molecule, differs from the ground state chemistry and provides a simple pathway to complicated structures, heavily obtainable by a classic synthetic approach. In this paper the polycyclic structures with oxygen, prepared by photo...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Croatian Society of Chemical Engineers
2007-03-01
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| Series: | Kemija u Industriji |
| Subjects: | |
| Online Access: | http://pierre.fkit.hr/hdki/kui/vol56/broj03/135.pdf |
| Summary: | Synthetic organic photochemistry, the chemistry of excited states of a molecule, differs from the ground state chemistry and provides a simple pathway to complicated structures, heavily obtainable by a classic synthetic approach. In this paper the polycyclic structures with oxygen, prepared by photochemical methodology of new o-substituted furan heterostilbenes are reviewed. The photochemistry of β-(2-furyl)-substituted-o-divinylbenzenes <b>6,13,15</b>, β,β-di(2-furyl)-substituted o-divinylbenzenes <b>18-20</b>, aryl and heteroaryl analogues of 2,3-distyrylfurans 33-36 is described. Due to steric reasons, on irradiation of β-(3-substituted-2-furyl)-o-divinylbenzenes 6, the preferred photoreaction was the intramolecular [2+2]-cycloaddition and formation of the bicyclo[2.1.1]hexenes <b>10</b> along with the formation of the corresponding phenanthrenes 12. On the other hand, furan analogues 6 and 13 give bicyclo[3.2.1]octadiene structures in very good yield. Di-substituted o-divinylbenzene derivatives <b>18-20</b> (with a hexatriene system as part of the aromatic ring) give bicyclo[3.2.1]octadiene derivatives <b>21-23</b> by intramolecular photocycloaddition and cyclophane derivatives <b>24-26</b> by intermolecular [2+2] two-fold photoaddition reaction. Compound 20 is the most selective of these o-divinylbenzenes yielding only the exo-bicyclo[3.2.1]octadiene derivative <b>23</b> at low concentrations, and only the cyclophane derivative 26 at high concentrations. This reaction to <b>23</b> and <b>26</b> is due - intra- or intermolecular complexation. Contrary to these results, on the irradiation of the aryl and heteroaryl analogues of 2,3-distyrylfurans <b>33-36</b> (with a hexatriene system as part of the heteroaromatic ring) different intra- and intermolecular processes have been observed. By intramolecular [2+2]-cycloaddition, this hexatriene system gives the phototransposition products. Also observed are stilbenes and phenanthrenes as secondary products obtained from the primary formed intermolecular cyclobutane adducts. |
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| ISSN: | 0022-9830 1334-9090 |