<p>This thesis describes free-radical reactions for the construction of tetrahydrofuran and pyrrolidine derivatives. The studies are concerned with (<i>i</i>) diastereoselectivity in radical cyclisation, (<i>ii</i>) construction of tetrahydrofuran-3-ones and pyrrolidin-3-ones <i>via</i> radical carbonylation/cyclisation and (<i>iii</i>) synthesis of tetrahydrofuran derivatives <i>via</i> group-transfer cyclisation of organochalcogen compounds.</p><p>(<i>i</i>) Diastereoselectivity in the synthesis of tetrahydrofuran derivatives <i>via</i> radical cyclisation was controlled by addition of Lewis acids. In the synthesis of 2,4-disubstitued tetrahydrofurans, the <i>trans</i>-isomer was formed as the major product in the unperturbed reaction. Upon addition of trialkylalumiums the diastereoselectivity was reversed. In a similar fashion, <i>exo</i>/<i>endo</i>-diastereoselectivity in the synthesis of bicyclic 2,3,4-trisubstituted tetrahydrofurans could also be controlled.</p><p>(<i>ii</i>) Procedures for construction of tetrahydrofuran-3-ones and pyrrolidin-3-ones were presented. Epoxides were ring-opened with benzeneselenolate or benzenetellurolate and the resulting <i>β</i>-hydroxyalkyl phenyl chalcogenides were vinylated using ethyl propiolate/NMM or <i>E</i>-1,2-bis(phenylsulfonyl)ethylene/NaH. The corresponding nitrogen analogues were accessed by <i>N</i>-vinylation of aziridines followed by benzeneselenolate ring-opening. The two types of organochalcogen radical precursors were then treated with TTMSS/AIBN under an atmosphere of carbon monoxide (80 atm) to afford tetrahydrofuran-3-ones and pyrrolidin-3-ones, respectively, in high yields.</p><p>(<i>iii) </i>Microwaves were found to induce group-transfer cyclisation of <i>β</i>-allyloxyalkyl aryl chalcogenides. Short time heating (3-10 min) at 250 <sup>o</sup>C in ethylene glycol was required to obtain tetrahydrofuran derivatives in 60-91% yield.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-4018 |
| Date | January 2004 |
| Creators | Ericsson, Cecilia |
| Publisher | Uppsala University, Organic Chemistry, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 946 |
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